U.S. Weekly Temperature Below Average First Time in 10 Months

Preliminary data from the National Climatic Data Center (NCDC) show that the temperature for the contiguous 48 states of the U.S. in the week ending October 13 was cooler than average for the first time in 10 months. After 43 consecutive warm weeks, the national average temperature was 1.8° below normal. This also brings the month-to-date temperature for October to -0.9° relative to average. For the week, cool temperatures prevailed in 5 out of 9 climate regions (Northeast, East North-Central, Central, West North-Central, and South). Both the Central and East North-Central were near to more than 5° below average.

CapitalClimate analysis of unadjusted data from 215 National Weather Service stations shows that 83% of locations were cooler than average, while only 13% were warmer.

Images (click to enlarge):
- Weekly average U.S. temperature departures from normal, weeks ending June 4, 2011 (20110604) through October 13, 2012 (20121013); CapitalClimate chart from NOAA/NCDC data
- Average U.S. temperature departure from normal (°C) for October 7-13, 2012
from NOAA/ESRL

September Global Temperature Tied For Warmest on Record

The National Climatic Data Center (NCDC) announced today that the globally averaged land and ocean surface temperature for September 2012 was tied with 2005 as the warmest since records began in 1880. For the year to date, the temperature is the 8th warmest on record.

CapitalClimate analysis of NCDC data shows that the temperatures for the last 16 Septembers beginning with 1997 have all been in the top 16 warmest Septembers (see chart).

From the NCDC:

The combined average temperature over global land and ocean surfaces for September tied with 2005 as record highest for September, at 60.21°F (15.67°C) or 1.21°F (0.67°C) above the 20th century average. The margin of error associated with this temperature is ±0.20°F (0.11°C).

September marked the 36th consecutive September and 331st consecutive month with a global temperature above the 20th century average. The last below-average September was September 1976 and the last below-average month was February 1985.

The global land temperature was the third warmest September on record, at 1.84°F (1.02°C) above the 20th century average of 53.6°F (12.0°C). The margin of error is ±0.45°F (0.25°C).

Higher-than-average monthly temperatures were most notable across central Russia, Japan, western Australia, northern Argentina, Paraguay, western Canada, and southern Greenland, while temperatures were below average across far eastern Russia, western Alaska, southern Africa, parts of the upper midwest and southeast United States, and much of China.

Record to near-record warmth over land from April to September and increasing global ocean temperatures in the eastern equatorial Pacific Ocean resulted in the first nine months of 2012 ranking as the eighth warmest such period on record, with a combined global land and ocean average surface temperature of 1.03°F (0.57°C) above the 20th century average of 57.5°F (14.1°C). The margin of error is ±0.18°F (0.10°C).

The January–September worldwide land surface temperature was 1.69°F (0.94°C) above the 20th century average, marking the sixth warmest such period on record. The margin of error is ±0.40°F (0.22°C).

Record Daily Low Temperatures in N.Y. Metro Area

Image (click to enlarge): U.S. daily minimum temperatures for October 13, 2012, from Unisys

The National Weather Service reports that new record low temperatures for October 13 were set this morning at several locations in the New York metro area:

..LOCATION.......NEW RECORD LOW.....PREVIOUS RECORD LOW.....YEAR.......
KENNEDY NY.............37...................40..............1988.......
NEWARK NJ..............34...................36..............1934.......
ISLIP NY...............32...................34..............1987.......
BRIDGEPORT CT..........33...................34..............1981....... 

The Newark climate history began in 1929. However, the Kennedy, Islip, and Bridgeport records did not begin until 1949, 1986, and 1948, respectively. At Central Park, where records began in 1869, the low of 38° at 6:37 am was well above the record of 33° in 1875.

The NWS also notes that, in the surrounding areas, sub-freezing temperatures ended the growing season in the following counties:

IN NEW YORK...ORANGE...PUTNAM...ROCKLAND...AND WESTCHESTER.  
IN CONNECTICUT...FAIRFIELD...NEW HAVEN...MIDDLESEX...AND NEW LONDON.  
IN NEW JERSEY...PASSAIC...BERGEN...AND WESTERN ESSEX.  

U.S. Heat Streak Extends Into October With 43rd Consecutive Week;September 16th Consecutive Warm Month, Warmest Year to Date By Far

Despite a cold outbreak in the central portion of the country, the U.S. heat streak has extended into its 43rd consecutive week. Preliminary area-adjusted data from the National Climatic Data Center (NCDC) for the week ending October 6, posted overnight, show that the contiguous 48-state average temperature was 0.1° above normal. This was the smallest positive margin since the streak began with the week ending December 17 of last year. In fact, the raw average of 215 major National Weather Service (NWS) stations was 0.3° below normal.

Of the 9 climate regions, 4 were cooler than normal: East North-Central, Central, West North-Central, and South. The South was the coolest at -2.5°. However, the Northeast and West were each 5° or more warmer than average.

Preliminary data for September show that the month averaged 1.8° above normal, vs. 1.2° for August. The fully-adjusted NCDC result for September, posted a few minutes ago, was 1.4° above the 20th century average:

The average contiguous U.S. temperature during September was 67.0°F, 1.4°F above the 20th century average, tying September 1980 as the 23rd warmest such month on record. September 2012 marks the 16th consecutive month with above-average temperatures for the Lower 48.

The warm season of April-September was the warmest on record:

The contiguous U.S. warm season, defined as the six-month period from April-September, had temperatures that were record warm. The six-month average temperature of 68.2°F for the Lower 48 was 2.6°F above average. The previous warmest April-September occurred in 1934 when the nationally-averaged temperature was 67.6°F.

It was also the warmest year-to-date and 12-month period of October-September:

The January-September period was the warmest first nine months of any year on record for the contiguous United States. The national temperature of 59.8°F was 3.8°F above the 20th century average, and 1.2°F above the previous record warm January-September of 2006. During the nine-month period, 46 states had temperatures among their ten warmest, with 25 states being record warm. Only Washington had statewide temperatures near average for the period.

The October 2011-September 2012 period was the warmest such 12-month period on record for the contiguous U.S., with an average temperature of 56.2°F, 3.2°F above average. This 12-month temperature average tied the June 2011-May 2012 period as the 3rd warmest of any 12-month period. The six warmest 12-month periods have all ended during 2012.

Images (click to enlarge):
- Weekly average U.S. temperature departures from normal, weeks ending June 4, 2011 (20110604) through October 6, 2012 (20121006); CapitalClimate chart from NOAA/NCDC data
- Weekly average NWS station temperature departures from normal, week ending October 6, 2012; stations listed alphabetically by state and 3-character station identifier; CapitalClimate chart from NWS data
- Average U.S. temperature departure from normal for September 30-October 6, 2012
from High Plains Regional Climate Center
- Average U.S. temperature January-September, 1895-2012, from NCDC

Earliest Measureable Snowfall in 17 Years at Duluth

September 30 Update: Through yesterday, the monthly temperature at Duluth was 0.5° above average. Today's average of +5° (through 5 pm local time) will raise the monthly average by another 0.1-0.2°.

Original post:
The National Service reports on the early snowfall Friday at Duluth, Minnesota:

0.1 inches of snow fell in the late evening hours of Friday, September 21, 2012 at Duluth. This is the earliest snowfall of the season in 17 years. On September 21, 1995, 0.1 of snow fell on that day also.

International Falls reported a trace of snow. The record 24-hour snowfall for September at Duluth was 2.4" on the 18th in 1991.

Through the first 22 days, September's temperature has averaged 1.0° above climatology at Duluth.

Attention Climate Conspiracists: NOAA Adjustments Show Summer 2012 3rd Hottest on Record

Attention climate conspiracists (lookin' at you, Tom Nelson-bot): The NOAA/National Climatic Data Center (NCDC) analysis for August 2012 is in, and it shows that Summer 2012 was tied for the 3rd hottest on record in the contiguous 48 states of the U.S. That's right, analysis of the raw National Weather Service (NWS) data and even the preliminary August adjustments from NCDC showed the summer would be at least tied with 2011 for second place, but the final analysis posted today lowered the August average by 0.1° to a tie with 2006 for 3rd place.

Rather than being 10th warmest, as the preliminary data indicated, August came in at 16th warmest with an average of 74.4°, nearly half a degree below the raw estimate of 74.8°. This is a pattern that CapitalClimate has seen since we started tracking weekly averages at the beginning of summer: The weekly raw averages from 200+ NWS stations are adjusted downward by NCDC, and the monthly averages end up being even more conservative.

From the NCDC summary:

The average temperature for the contiguous U.S. during August was 74.4°F, 1.6°F above the 20th century average, marking the 16th warmest August in a period of record that dates back to 1895.

Higher-than-average temperatures occurred across much of the West, where Nevada tied August 1934 as its warmest August on record, with a statewide temperature 4.0°F above average. Six additional states across the region had August temperatures ranking among their ten warmest. Much of the Northeast was also warmer than average, where five states from Maine to Delaware had monthly temperatures among the ten warmest.

Much of the Central U.S. had near to below average August temperatures, with lower-than-average temperatures across the Ohio Valley and the Southeast.

The warmer than average August, in combination with the hottest July and a warmer than average June, contributed to the third hottest summer on record for the contiguous United States. The summer season’s nationally-averaged temperature was 74.4°F, 2.3°F above the 20th century average. Only the summers of 2011 (74.5°F) and 1936 (74.6°F) had higher temperatures for the Lower 48.

The summer season was warmer than average for a large portion of contiguous United States, with the exception of the Southeast and parts of the Northwest. Sixteen states across the West, Plains, and Upper Midwest had summer temperatures among their ten warmest. Colorado and Wyoming each had their record hottest summer, with seasonal temperatures 4.4°F and 4.9°F above average, respectively. Much of the Northeast was warmer than average, where seven states from New Hampshire to Maryland had a top ten warm summer.

Images (click to enlarge):
- Hottest U.S. average summer temperatures, CapitalClimate chart from NCDC data
- Statewide average temperature ranks, Summer 2012, from NCDC
- U.S. average temperature departures from normal, August 2012, from NOAA/HPRCC
- Statewide average temperature ranks, August 2012, from NCDC

Only 4% of U.S. Cooler Than Average as Fall Begins With 39th Consecutive Warm Week

CapitalClimate analysis of temperature data from 215 National Weather Service (NWS) stations shows that the week ending September 8 was 4.0° above average in the contiguous 48 states of the U.S. Just 9 locations, or 4% of the total, were cooler than normal. This is the 39th consecutive week with above-average temperatures. Except for one week in early December, every week in the past winter, spring, and summer has now been warmer than normal.

Here is the complete list of NWS locations which were cooler than average for the week (alphabetically by state):

State  City      ID    Departure
CA SAN FRANCISCO SFO    -3
CA STOCKTON      SCK    -1
FL KEY WEST      EYW    -1
ID POCATELLO     PIH    -1
MT BUTTE         BTM    -2
MT HAVRE         HVR    -2
ND JAMESTOWN     JMS    -1
ND WILLISTON     ISN    -1
SD ABERDEEN      ABR    -1