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 10th 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.