Showing posts with label Washington DC Weather Records. Show all posts
Showing posts with label Washington DC Weather Records. Show all posts

Sunday, March 16, 2014

Washington DC Climate: March 2014

Latest update: March 23
For daily updates most days around 6 pm EDT:



March is on track for an average temperature of 42.7°, which would be 4.1° below the long-term average and the coldest since 1993, when it was 42.2°. Precipitation remains below average.

Washington DC daily temperature departures from normal and monthly average to date (click to enlarge):


Washington DC daily precipitation and monthly departure from normal to date (click to enlarge):


CapitalClimate charts from National Weather Service data. Background image from Kevin Ambrose.

Friday, February 28, 2014

Washington DC Climate: February 2014

Latest update: February 28
For daily updates most days around 5 pm EST:



Final February charts:

Washington DC daily temperature departures from normal and monthly average to date (click to enlarge):


Washington DC daily precipitation and monthly departure from normal to date (click to enlarge):


CapitalClimate charts from National Weather Service data. Background image from Kevin Ambrose.

Friday, January 31, 2014

Washington DC Climate: January 2014

Washington DC daily temperature departures and monthly average to date (click to enlarge):


Washington DC daily precipitation and monthly departure to date (click to enlarge):


CapitalClimate charts from National Weather Service data. Background image from Kevin Ambrose.

Friday, December 6, 2013

It Hasn't Cooled Since 1989;
Washington December Daily Low Temperature Records


Images (click to enlarge): December daily record low temperatures for Washington, DC, by year of occurrence; Number of December daily record lows per decade; CapitalClimate charts from National Weather Service data

If you can remember the last time Washington, DC set a daily record low temperature in December, you've been hanging around too long in Babble-On on the Potomac. It was the first year of the G.H.W. Bush administration when a record low of 7° was set on December 23, 1989. The high of 22° that day was also a record low maximum for the date. Since then, there have been no new December record daily lows in the decades of the 1990s, 2000s, or so far in the 2010s. The only other decade with no December cold records was the 1950s.

Here are some other statistics of Washington December low temperature records:
- Half (15) of the daily records were set over 100 years ago, from 1872 through 1904, and 2 more were set 99 years ago.
- The 1880s had the most records of any decade with 7, followed by the 1910s with 5. Interestingly, all of the 1880s records occurred in even-numbered years.
- Except for the 1980s (4 records), no decade since the 1910s has had more than 2 records.
- The all-time coldest December temperature was -13° on December 31, 1880. This was just 2° warmer than the all-time Washington low of -15° on February 11, 1899. It was also a record -7° on December 30, 1880. These are the only December dates with lows below 0°.

Monday, April 8, 2013

Washington Has Latest Occurrence of First 75° Temperature*


* since 2001

5:30 PM Update: The preliminary high for the day was 79° at 3 pm EDT.

Original Post:
With a noon temperature of 70°, Washington is well on its way to the first 75° or higher temperature of the year by this afternoon, or at least by tomorrow. This will be the latest occurrence of the first 75° temperature . . . since 2001, when this temperature was reached on April 9. The latest occurrence on record at the current observation location was on April 26, 1984. The average date for the first 75° temperature since 1930 is March 16.

Monday, April 1, 2013

Washington Fails to Reach 65° in March, First Time Since 1958



March 2013 has closed out the record books with a monthly high temperature in Washington of 63°. This is the coldest high for March since the 58° in 1958. It's only the second time Washington has failed to reach 65° in March since the 60° high in 1931.

The unofficial monthly average of 43.8°, however, was only 3.0° below normal, making this the 55th coldest March since temperature records began in 1871.

Thursday, March 21, 2013

Think It Was Cold Today, DC? Not Your Great-Great Grandfather's March of the Penguins



Denizens of the DMV were complaining about the early-spring cold this March 21, but the chill was nowhere near the historical extremes for this date or any other date through the end of the month. Although the high for the day of 42° was set shortly after midnight, the daytime temperatures were mostly in the 30s. On the other hand, the afternoon high did reach 41°. This was well below the historical average of 58° in Washington, DC, but it was also a full 10° above the coldest high temperature for the date, which was set in 1885. In fact, it would not be near any coldest high for the remainder of March.

The CapitalClimate chart from National Weather Service data shows that all but 1 of the 13 record coldest high temperatures from March 19-31 were set over 100 years ago. The one exception was 73 years ago, on 03/25/1940.

Wednesday, March 6, 2013

Washington March Snow: Rare Event Becoming Rarer?



The climatological average for March snowfall in Washington is just 1.3", so significant snowfalls in the first month of meteorological spring are rare. With the bust of the current "Snowquester", it's likely that 2013 will add to a string of nearly snowless Marches extending back to 2009, when a total of 5.5" was recorded.

In the early days of official snowfall records, which began in Washington in 1888, March snow was relatively common. In fact, the first 6 years in the climate record had measurable March snow; 3 of those were over 10".

The chart shows on the horizontal axis all of the years with 4" or more of total snowfall in March. The vertical axis is the number of years since the previous occurrence of 4"+. For example, if 4" occurred in consecutive years, the interval would be shown as 1. For the first several decades, the interval between significant March snows never exceeded 4 years, but in 1923 it reached 9. The interval reached double digits for the first time in 1956, when it was 13. It was 13 again in 1993, and 10 in 2009, which ended a March snow dry spell that began after 1999.

Unless this month has a miraculous snowfall recovery, the current March snow drought will be 4 years and counting.

Monday, February 18, 2013

SnowNoGettin': Washington on Track for Record Lowest 3-Year Total Snowfall, Largest 3-Year Decrease



As the massive snowfalls of the 2009-1010 season fade into the rear-view mirror, Washington DC is close to ending meteorological winter with a near-record low 3-year snow total. With the latest nor'easter bombing out well offshore, there is no Presidents' Day snowfall this year, and model indications are that there will be little, if any, snow in the next 10 days. That would end meteorological winter with a puny 1.5", the lowest since the 0.1" in November 1997 through February 1998. For the past 3 years, the winter total of 13.4" is likely to be the second lowest on record, ahead of the 14.1" in the 3-year interval ending in 2008-09. This means that two of the three lowest 3-year totals will be the periods immediately preceding and following the record season of 2009-2010.

For the entire season (including all months), assuming no more snow in February, the highly erratic month of March would have to contribute nearly 5" for the 3-year seasonal total to exceed the current record low for the period ending in 1998-99.

Comparing consecutive 3-year totals, the current amount of 13.6" is a massive 54.6" less than the 3-year total ending last year, which included the record high season. This is over 13" more than the 3-year decrease observed in 1901-02, the current record decrease.

Images (click to enlarge):
- Washington 3-year snow totals ending at season indicated
- Lowest Washington 3-year winter-only (November-February) snow totals
- Lowest Washington 3-year snow totals (2013 to date)
- Largest decreases in consecutive 3-year Washington snow totals (2013 to date)
CapitalClimate charts from National Weather Service data; background image © Kevin Ambrose

Tuesday, December 25, 2012

Washington on Track for Second Consecutive Top-10 Warmest December


January 2 Update: Temperatures continued to exceed forecasts through the end of the month. The final average was 45.3°, which was 5.6° above normal. The 31st, at 1° cooler than average, was only the 3rd day all month with temperatures below average.

December 29 Update: Warmer-than-forecast temperatures have pushed the projected December average to 45.2°, displacing 2011 as the 6th warmest on record (chart updated).

Original post:
As of today, the month-to-date average temperature for Washington DC is a toasty (for December) 47.0°. Even with forecast temperatures averaging near seasonal normals for the remaining 6 days of the month, the projected monthly average of 45.0° should be enough to tie with last year for the 6th warmest December since records began in 1870. As noted earlier, the warm December will close out a record warm year by what is virtually guaranteed to be a huge margin.

Monday, December 10, 2012

Counting Down to Washington's Record Warmest Year: "It Hasn't Warmed Since 2012!"

Record Hot Year Countdown Scorecard

Date  High Low 2012-YTD 1991-YTD Departure to Miss 
12-10 63   49   62.7      61.5    -18.1    
12-11 62   41   62.6      61.4    -19.5 
12-12 47   39   62.6      61.4    -20.7  
12-13 50   35   62.5      61.4    -22.1 
12-14 52   30   62.5      61.4    -23.4 
12-15 54   37   62.4      61.3    -25.2
12-16 52   46   62.4      61.2    -27.6
12-17 55   48   62.4      61.1    -30.5
12-18 62   43   62.3      61.1
12-19 54   36   62.3      61.0
12-20 53   41   62.2      60.9    -41.0  
12-21 59   39   62.2      60.8
12-22 45   35   62.1      60.8
12-23 47   29   62.1      60.7
12-24 41   31   62.0      60.7
12-25 51   34   61.9      60.6 
12-26 45   33   61.9      60.5
12-27 43   37   61.8      60.5
12-28 45   36   61.8      60.4
12-29 42   34   61.7      60.4
12-30 42   32   61.6      60.3
12-31 41   29   61.6      60.2 
(Departure to Miss indicates how much the average temperature must be below normal for the rest of the year in order to avoid setting a new record for warmest year.)

January 2 Update: Thanks to a quirk in calculation methodology, the National Weather Service is rounding down the final average to 61.5°. It was also the record warmest year at Washington Dulles and the 3rd warmest at Baltimore. From the NWS report:
2012 WAS THE WARMEST YEAR ON RECORD FOR WASHINGTON DC WITH AN ANNUAL AVERAGE TEMPERATURE OF 61.5 DEGREES. THE PREVIOUS WARMEST ANNUAL AVERAGE TEMPERATURE ON RECORD WAS 60.2 DEGREES IN 1991. THE AVERAGE TEMPERATURE FOR 2012 WAS 3.3 DEGREES ABOVE THE 1981-2010 NORMAL AND WOULD BE COMPARABLE TO THE NORMAL ANNUAL TEMPERATURE OF ATLANTA...OKLAHOMA CITY AND SAN JOSE...JUST TO NAME A FEW LOCATIONS.

DULLES ALSO EXPERIENCED THEIR WARMEST YEAR ON RECORD WITH AN ANNUAL AVERAGE TEMPERATURE OF 57.9 DEGREES IN 2012. THE PREVIOUS WARMEST YEAR ON RECORD WAS 1998...WHEN THE ANNUAL AVERAGE TEMPERATURE WAS 57.1 DEGREES. THE 2012 AVERAGE TEMPERATURE WAS 2.6 DEGREES ABOVE THE 1981-2010 NORMAL.

2012 WAS THE THIRD WARMEST YEAR ON RECORD FOR BALTIMORE WITH AN ANNUAL AVERAGE TEMPERATURE OF 58.6 DEGREES. ONLY 1931 AND 1949 WERE WARMER WHEN THE ANNUAL AVERAGE TEMPERATURES BOTH YEARS WERE 59.2 DEGREES. THE 2012 AVERAGE TEMPERATURE WAS 3.5 DEGREES ABOVE THE 1981-2010 NORMAL.

December 31 Update: The 42/32 temperatures yesterday and 41/29 today give a final unofficial yearly average of 61.6°, so the record is broken by the higher amount of 1.4°. (Chart updated)

December 29 Update: Today's high of 42° exceeded expectations by 4°, so the gap to a final yearly average of 61.6° has narrowed to less than 0.004°. A miss of Monday's forecast low of 26° could be the clincher.

December 28 Update: Today's +4° temperature departure means the remaining 3 days need to average -0.5° or warmer to clinch a 1.4° excess over the old annual record. The forecast is for a deficit of 2.1°, however.

December 27 Update: Thanks to continued above-average temperatures, a departure of just 1° in the next 4 days would be enough to raise the final yearly average to 1.4° above the old record.

December 25 Update: Yesterday was just the second day this month with cooler than average temperatures (2° below). Today's high outpaced expectations, however, as so many recent days have done. The year-to-date average is outpacing the previous record by 1.3° at 61.9°. With less than a week now remaining, it is now highly likely that the final yearly average will break the record by that amount. The forecast temperatures for the next 6 days average exactly equal to normal, and the average would have to be at least 5° colder in order to avoid a final average 1.3° above the old record. On the other hand, a departure of just +1.2° for the final 6 days would raise the yearly average by another 0.1°.

December 17 Update: Today's low of 48° through 5 pm is 2° above the normal high. At this point, even if temperatures set new record lows and record cold highs for every day in the next 2 weeks, it will still be a record warm year.

December 15 Update: While it's technically not impossible, Washington would now have to set a new record low temperature every day for the next 16 days in order to avoid setting a new record high annual temperature. (See scorecard above.)

December 13 Update: The temperature departure from normal required to avoid setting a new record is now over 22° for every day for the rest of the year. Since that is clearly not happening soon, we are verging on the realm of physical impossibility to avoid a record. The average of all record low temperatures for every day from the 14th through the 31st is -25.5° relative to normal.

December 12 Update: Yesterday's high/low temperatures went virtually midnight to midnight; the final values of 62°/41° averaged out 11° above normal. Today was considerably colder, but the 47°/39° range was still 3° on the warm side. Using the forecast temperatures for the next 7 days and climatology for the remainder of the month yields a projected yearly average of 61.4°. It would have to average almost 21° below normal for the rest of the month in order to avoid breaking the previous record.

Original post:
With just 3 weeks remaining before New Year's Eve, it's becoming increasingly evident that the climate denialists will have to find a replacement for the tired old talking point, "It hasn't warmed since 1998." As the November climate summary showed, 2012 is well on its way to being the warmest on record in the U.S. contiguous 48 states. That will most likely be true in many individual locations as well, particularly in Washington DC.

While well below the record for December 10, today's high of 63° was 15° above average, and the low so far of 49° is a degree above the normal high. This puts the average for the month over 50°, more than 7° above normal to date. If this were to continue through the end of the month (extremely unlikely), it would be the warmest December on record by over 4°.

The year-to-date average temperature of 62.7° is 1.2° above the pace of the previous record warmest year of 1991. If the remaining 3 weeks average just normal (high/low range of 48/34 currently, declining to 44/29 by the 31st), the final 2012 average (marked "Climo" on the charts) will still be 1.1° above the old record. This is a huge amount for a yearly average, as indicated by the top-10 chart, which shows only a 0.9° difference between the current record and the 10th place year of 2002.

It will certainly be colder between now and the end of the month, but how much colder would it have to be to avoid breaking the record? Assuming today's low remains unchanged through midnight, the remaining 21 days of December would have to average an eye-popping -18.1° relative to normal just to tie with 1991. That means an average high for 3 weeks below 30° and an average low below 16°. While such a frigid blast is not physically impossible, it would take an incredibly intense and fanatical belief in the Ice Age Fairy to think that it will happen.

Stay tuned; we'll keep you posted as this historic event unfolds.

Note: While not unexpected, these results were so extreme the the Climate Capitalist suspected that the data monkeys down at Momma Nature's Weather Grill had gotten into the eggnog a bit early. A cross-check of the daily year-to-date values with the monthly averages and a comparison of the projection with a hand calculator confirmed the data, however.



Thursday, November 29, 2012

Washington's 7th Driest November;
Second Biggest October/November Relative Decrease


November 30, 5 PM Update: Added 2012 monthly data and charts.

Original post:
With the mere 0.06" of light rain on Tuesday, November 2012 will close out tomorrow with only 0.60" of precipitation at Washington. That ties it with 1908 as the 7th driest November in 143 years of climate history. The driest was in 1981, when 0.29" was reported.

This exceptionally dry month, following the 5.82" drenching in October, represents slightly less than a 90% month-to-month decrease, second only to the 92% in 1981. In absolute terms, the 5.22" rainfall reduction is the 5th largest on record. The largest absolute October-November decrease was 7.49" in 2005, following the all-time wettest October.

Following wetter-than-average months in September and October, this is now the 9th month of 2012 with below-average precipitation. The November departure of 81% below average is followed by March with a 71% deficit.

The 29.42" total precipitation through the first 11 months is over 7" below the average amount to date. If December rainfall is equal to climatology, the annual amount (marked "Climo" on the chart) will remain the second driest since 2000, behind the 29.95" in 2001. Of the 13 years so far this century, only 4 others have been below average.

November was very dry throughout the Mid-Atlantic region, with nearly all areas below 50% of normal. Large areas from Washington eastward and southward have been below 25% of normal. The 0.71" at Baltimore is less than 22% of normal, and the 1.12" at Dulles is 33% of normal. Richmond's 0.27" is 8% of normal and the 5th driest in records dating back to 1872.






Tuesday, October 30, 2012

Preliminary Data: Sandy Precipitation Breaks Mid-Atlantic Records

October 30, 7 PM Update: Based on daily records from the National Climatic Data Center, yesterday's rain from Sandy was also the 5th wettest day of any month in Baltimore climate history dating back to 1871. It was the highest precipitation for any day other than in the months of July through September.

October 30, 4 PM Update:
The Washington National daily total of 3.85" is confirmed by the National Weather Service. The amounts at Washington Dulles and Baltimore were all-time daily records for the month of October:
A RECORD DAILY MAXIMUM RAINFALL OF 4.25 INCHES WAS SET AT WASHINGTON   
DULLES DC YESTERDAY. THIS BREAKS THE OLD RECORD FOR THE 29TH OF 1.03   
INCHES SET IN 2011.   
  
YESTERDAY'S RAINFALL WAS ALSO THE WETTEST CALENDAR DAY IN OCTOBER AT   
DULLES. THE PREVIOUS WETTEST OCTOBER DAY WAS 1 OCTOBER 1979...WHEN   
4.06 INCHES OF RAINFALL WAS OBSERVED.  

A RECORD RAINFALL OF 5.51 INCHES WAS SET AT BALTIMORE MD YESTERDAY.   
THIS BREAKS THE OLD DAILY RECORD FOR THE 29TH OF 1.51 INCHES SET IN   
1973. YESTERDAY'S RAINFALL WAS ALSO THE WETTEST CALENDAR DAY IN   
OCTOBER AT BALTIMORE. THE PREVIOUS WETTEST OCTOBER DAY WAS 10   
OCTOBER 1922...WHEN 4.38 INCHES OF RAINFALL WAS OBSERVED.  
Records were also set at Philadelphia, Atlantic City (more than doubling a 104-year-old record), Wilmington, Avoca PA, Pittsburgh, Harrisburg, Rochester, and Buffalo. According to the National Climatic Data Center, the records at Wilmington and Atlantic City were also all-time October daily records. The Washington National amount was an all-time October record at the current location (76 years). The NWS reports:
A RECORD DAILY RAINFALL AMOUNT OF 2.68 INCHES WAS SET AT THE   
PHILADELPHIA INTERNATIONAL AIRPORT. THIS BREAKS THE PREVIOUS RECORD   
OF 1.72 INCHES SET BACK IN 1953.   

A RECORD RAINFALL OF 4.79 INCHES WAS SET AT ATLANTIC CITY NJ   
YESTERDAY. THIS BREAKS THE OLD RECORD OF 2.33 SET IN 1908.  

A RECORD RAINFALL OF 3.79 INCHES WAS SET AT WILMINGTON DE YESTERDAY.   
THIS BREAKS THE OLD RECORD OF 2.56 SET IN 1953.  

A RECORD RAINFALL OF 1.64 INCH(ES) WAS SET AT AVOCA PA TODAY.   
THIS BREAKS THE OLD RECORD OF 1.39 SET IN 1953.  

A RECORD RAINFALL OF 1.72 INCH(ES) WAS SET AT PITTSBURGH PA   
YESTERDAY. THIS BREAKS THE OLD RECORD OF 1.19 SET IN 1973.  

A RECORD RAINFALL OF 2.93 INCHES WAS SET AT HARRISBURG YESTERDAY.   
THIS BREAKS THE OLD RECORD OF 1.87 SET IN 1935. A CONTINUOUS WEATHER RECORD HAS BEEN KEPT AT HARRISBURG SINCE 1888.  

A RECORD RAINFALL OF 1.44 INCHES WAS SET AT ROCHESTER NY YESTERDAY.   
THIS TIES THE OLD RECORD OF 0.71 SET IN 1935.  

A RECORD RAINFALL OF 1.42 INCHES WAS SET AT BUFFALO NY YESTERDAY.   
THIS TIES THE OLD RECORD OF 1.21 SET IN 1917.  
Original post:
The unofficial total rainfall today of 3.85" at Washington not only breaks the record for October 29 (2.69" in 1885) by over 1", but it is also the highest precipitation so late in the season. It's the second highest daily amount for any day in October, and it's the only time over 3" has been observed later in the year than October 25, except for the 3.10" on December 7 last year.

Monday, October 29, 2012

Post-Tropical Hurricane Sandy Threatens Mid-Atlantic Low Pressure Records

Oct. 30, 2 AM Update: NWS is reporting that the Baltimore low pressure was 964.4 mb, beating the old record by 1.5 mb.

Midnight Update: Preliminary data indicate that Washington bottomed out at 28.63"/969.5 mb, and Baltimore hit 28.49"/964.9 mb. This would break the Baltimore record by 1 mb.

Original post:
The National Weather Service reports that the post-tropical phase of Hurricane Sandy could threaten the modern record for low pressure readings at Washington and Baltimore:
PRELIMINARY INFORMATION ON LOWEST PRESSURE RECORDED AT WASHINGTON DC 
AND BALTIMORE MD...BOTH MEASURED IN THE MARCH 1993 SUPER STORM...

WASH DC... 28.54 INCHES HG 966.5 MB MEASURED AT 23Z ON 13 MARCH 1993 
BALT MD... 28.52 INCHES HR 965.9 MB MEASURED AT 00Z ON 14 MARCH 1993

THESE VALUES WERE ARRIVED AT BY SEARCHING AN INTERNAL DATABASE OF 
OBSERVATIONS MAINTAINED UNOFFICIALLY HERE AT THE WEATHER OFFICE. 
THE DATABASE GOES BACK TO 1929. 

Thursday, July 26, 2012

Washington Breaks Monthly Record With 7th 100° Day

Today's high temperature at Washington of at least 100° as of the 5 pm report marks the 7th time this month that the temperature has reached triple digits. That breaks the record of 6 in July 1930. This also keeps the month firmly on track for the second hottest month in Washington history.

The previous 100° days this month:
Date   High Temperature
5 100
6 100
7 105
8 102
17 100
18 101

Wednesday, July 25, 2012

Washington Still on Track for 3rd Consecutive Top-3 Hottest July/Hottest All-Time Month

Image (click to enlarge): Hottest July average temperatures vs July 2012 to date (TD) and projected (PROJ) at Washington DC; CapitalClimate chart from National Weather Service data

Forecast Actual Projected
Date High Low High Low Average
27 97 77 95 77 83.8
28 94 73 97 74 83.9
29 91 72 90 72 83.9
30 89 69 89 75 83.9
31 88 71 90 74 84.0
July 31, PM Update: Once again, the temperature has outperformed expectations, with another high of 90°. This gives a final monthly average of 84.0°, the second hottest month in Washington climate history.

July 30, PM Update: The preliminary high/low temperatures are enough to keep the projection at 83.9°, even if the high tomorrow is only 84°. A high of 85° or higher would push it up to 84.0° as long as the low is at least 74°.

July 29, PM Update: The daily high underperformed the original forecast by 1°, but the current outlook for the next 2 days keeps the projected monthly average at 83.9°.

July 28, PM Update: Today's preliminary average temperature exceeds the forecast by 3.5° and raises the projected monthly average to 83.9°.

July 27, PM Update: Today's high of 95° underperformed the forecast by 2°, but the projection remains the same.

July 26 Update: Today's high/low temperatures of 100°/74° raise the month-to-date average to 84.1°, while the projected average is back to 83.8°.

In order for the final average to avoid being the second hottest month on record, the next 5 days would have to be at least 4.5° below the forecast (see table above).

5:30 PM Update: Since the chart was made, today's preliminary daily high has reached 89°, pushing the projected monthly average temperature up another tenth of a degree to 83.9°.

Original Post:
As noted last week, the first half of July put Washington firmly on track for a top-3 hottest July (and therefore top-3 hottest all-time month) for the third consecutive year. Despite a daily record low maximum temperature, the monthly average to date of 84° is still within half a degree of last year's record and well above the second place 2010 (tied with 1993).

With forecast temperatures near a possible monthly record 7th 100° reading tomorrow and upper 90s on Friday, even a return to more seasonable levels by the 31st puts the projected monthly average at 83.8°, halfway between July 2010 and 2011. At this point, temperatures for all of the next 6 days would have to average at least 4° below the forecast in order for this July to drop below second place on the all-time hottest list.

Saturday, July 21, 2012

A Mid-Atlantic Cold Day in July

July 22 Update: For the record, the National Weather Service report:
A RECORD LOW MAXIMUM TEMPERATURE OF 71 DEGREES WAS SET AT WASHINGTON   
NATIONAL DC YESTERDAY...JULY 21ST. THIS BREAKS THE OLD RECORD OF 74
DEGREES THAT WAS SET IN 1984...1939 AND 1886.
The Dulles and Baltimore/BWI records were 69°.

1 AM Update: And the 1 am temperature is again 70°, so the new record low maximum is pretty well set.

Some remedial math for Tom Nelson fans:
Total area of District of Columbia: 68 sq. mi.
Total area of Maryland: 12407 sq. mi.
Total area of U.S.: 3,794,100 sq. mi.
Total number of days in July: 31

Midnight Update: The temperature has held at 70° for 5 out of the last 6 hours, so the final high is likely to remain at 71°, setting a new record for July 21.

Attention Tom Nelson fans: Here is the context he's left out:
Washington on Track for 3rd Top-3 Hottest July in As Many Years

Original Post:
Some sun could still break through and nudge the temperature up a few degrees, but the high temperatures so far today in the Washington/Baltimore area are likely to break records for the coldest maximum on July 21:
Location            High Departure Previous record
Washington National 71 -18 74 /1984
Washington Dulles 68 -20 75 /1984
Baltimore BWI 69 -18 73 /1984
Although the 18 to 20 degree departures from average are spectacular, the same low clouds, drizzle, and light rain which depressed the daily highs have also kept the daily lows elevated, so the overall averages are in the -10° to -11° range relative to climatology.

The daily average of 69° at Washington National, if it holds, will be the 3rd coldest July 21 since 1929, when the average was 68°. The average on this date in 1939 was 68.5°. The low in 1929 was accomplished the old-fashioned way, with a daily low of 58°. The record low for July 21 was 56° in 1909.

Wednesday, July 18, 2012

Washington on Track for 3rd Top-3 Hottest July in As Many Years

The high of 101° so far this afternoon at Washington ties July 1930 with the 6th 100°+ temperature for the month. It also puts this month firmly ahead of the pace of last July's all-time hottest month with an average of 86.0°, vs 84.5° in 2011. Even with a 20° cooldown to a forecast high of 81° on Saturday, a projection based on predictions through Tuesday the 24th and climatological averages for the remaining week of the month would put the July average at 83.4°, still ahead of the then record-tying July 2010. That would make the last 3 Julys the hottest on record. The only remaining top-10 hottest July before 1980 will be 1955.

For the summer to date, the National Weather Service reports:
INCLUDING TODAY...THE HIGH TEMP HAS REACHED OR EXCEEDED 95F ON 18 DAYS AND 100F ON 7 DAYS SO FAR THIS YEAR...WHICH ARE BOTH THE MOST ON RECORD THROUGH 18 JUL AT DCA. PRIOR TO THIS YEAR...THE MOST 95-DEGREE AND 100-DEGREE DAYS THROUGH 18 JUL WAS 16 IN 1991 AND 5 IN 1988...RESPECTIVELY. THE MOST 95-DEGREE AND 100-DEGREE DAYS ON RECORD THAT OCCURRED IN A CALENDAR YEAR WAS 28 IN 1980 AND 11 IN 1930...RESPECTIVELY.

Saturday, July 7, 2012

Washington's Triple Triple Locks In Hottest First Week of July;
Earliest 105° on Record

5 PM Update: The Washington temperature has hit at least 105°F (40.6°C) as of 5 pm, within 1°F of the all-time high temperature record. This is also the earliest 105°F; the previous record was July 10, 1936.

Original Post:
The record high temperature of 104° so far today breaks the record of 102° set just 2 years ago and marks the third consecutive day with 100°+ temperatures in Washington. Along with the morning low of 82°, this virtually guarantees that the current week will close out as the hottest July 1-7 in Washington weather records. Since data collection began at or near the current National Airport location in 1929, the previous hottest first week of July was in 1999, when the average was 86.1°. Assuming no further change in today's readings, the 7-day average will be 88.9°. This is 7° above the pace of last year's all-time hottest month. In order to avoid breaking the weekly record, today's low would have to drop to at least 46°.

Monday, May 28, 2012

Counting Down to the Record: Washington Temperature Approaches Reaches Exceeds 1° Above Warmest Spring, Heads Higher



June 1, 2 PM Update: Charts updated above. Note that the May average of 71.4° was 5.4° above the climatological average and the 3rd warmest May on record, behind 1991 and 2004. It was only the 4th time in history that May averaged over 70°.

June 1, 1 AM Update: The midnight (standard time) temperature is 74°. The daily low remains 69°, and the new record for warmest spring stands at 62.2°. (Charts to be updated.)

May 31, 6 PM Update: Today's high of 85° has exceeded expectations by 3°, and the morning low of 69° is a whopping 11° above the forecast from last evening. That's enough to push the semi-final spring average up another 0.2° to 62.2°, an incredible 1.5° above the old record. With cooling temperatures this evening, however, it all comes down to the midnight temperature (1 am EDT). A reading of 63° or lower would shave off 0.1° and put the final average at 62.1°.

May 30, PM Update: Yesterday's high/low temperatures were 91°/70°. While today's high of 83° as of 5 pm was held down by persistent clouds, the spring average to date has been lifted to 62.0°, exceeding the old record by 1.3°. Tomorrow's cooler readings should still be enough to raise the final average by another 0.1°. (Charts updated above.)

Meanwhile, preliminary indications are still confirming that the U.S. 48-state average spring temperature will crush the old record. See here for the latest update.

May 28, PM Update: Today's preliminary high of 90° brings the month to date average temperature up to 61.7°, a full degree above the old record. The projection remains the same.

Original post:
As noted previously, Washington DC is headed to the record warmest spring by an unprecedentedly large margin. Following the low this morning of 70°, the high temperature so far today (through 1 pm) of 86° is enough to raise the March-May average to date to 61.6°, which is 0.9° above the old record from 1977. Given the forecast temperatures for the next 3 days, the projected final average will be 62.2°. Even without reaching the 90° levels predicted for this afternoon and tomorrow, the average will continue rising. In order to decline from the current level, the average for the next 3 days will have to be at least 8° below the historical average through the 31st. That would mean a high of 71° and a low of 53°. Although that's hardly impossible, it's fair to say: Ain't. Gonna. Happen. While it's bad form to predict records days before before they occur, this one is about as sure as you can get.

Stay tuned as we count down the record.

Seasonal Outlook

Latest seasonal forecast: Click here.


Latest 3-month temperature outlook from Climate Prediction Center/NWS/NOAA.