Monday, November 1, 2010

New Record Highs Continue Outpacing Lows By Wide Margin: Nearly 5:1 in October

For related record temperature posts, see:
Continuing the pattern established in the spring, extending through the summer and into September, new record high temperatures are outpacing record low temperatures in the U.S. for the 8th consecutive month. Preliminary data from the National Climatic Data Center (NCDC) for October show over 1500 new record highs, vs. slightly more than 300 lows, giving a ratio of 4.75 to 1. For the year to date, new highs are exceeding new lows by a ratio of 2.8 to 1.

Reversing the trend in September, new record warm minimum temperatures also exceeded record high maximums as they have in nearly every month so far in 2010. The excess of high minimum records was particularly strong in the summer, when as many as 3761 were reported in August alone.

With the exception of a cold spell from October 5th through 7th, record highs equaled or exceeded record lows every day of the month. The large monthly excess of heat records vs. cold records was driven by two very warm spells, one in each half of the month. The first one, around Columbus Day, peaked on the 11th, when 194 record highs were set, vs. only 1 record low. In a 3-day period, 530 heat records were set, over 50% more than the cold records for the entire month.

In connection with the Minnesota Maxi-cyclone late in the month, many more records were set in the eastern half of the country. There were 325 individual record high temperatures from the 26th through the 28th, more than the total lows for the whole month. During the same 3 days, there were only 18 record lows.

Images (click to enlarge):
- Total number of daily high temperature, low temperature, and high minimum temperature records set in the U.S. for spring 2010 (March-April-May) and monthly from June through October 2010, data from NOAA National Climatic Data Center, background image © Kevin Ambrose ( Includes historical daily observations archived in NCDC's Cooperative Summary of the Day data set and preliminary reports from Cooperative Observers and First Order National Weather Service stations. All stations have a Period of Record of at least 30 years.
- Daily numbers of high and low temperature records set in the U.S. for October 2010, data source as above


Anonymous said...

I have a more pedestrian question re. DC weather. How can I determine if there will be dew on my car the next morning. It's a pain to clean off my car when this happens. However, I have a covered parking option that is a little further of a walk from my bldg. Any clues I should look for?

CapitalClimate said...

That's an interesting question, because there are several variables involved. The most important factor is the temperature vs. the dewpoint. In order for dew (or frost) to form, the temperature of the surface (not necessarily the air) must be at or near the dewpoint, so the water vapor in the air will condense. You can look at the dewpoint in the evening and compare that with the forecast low temperature for the next morning. If the low is expected to be within a few degrees of the dewpoint, there's a good chance you'll see dew on your car. If the sky is clear or partly cloudy and the wind is light, that increases the odds.

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