Has this been an unusually hot start to summer?

The recent stretch of warm, humid weather has got some people wondering if we have gotten off to an unusually hot start to summer this year in Madison.

There are a couple of ways one could approach that question. One way is to consider the departure from average for our daily high temperatures since May 1. From that perspective, we have been consistently warmer than normal with May daily highs averaging 3.2 degrees above normal and, June (through Friday) averaging 1.9 degrees above normal.

Another, somewhat more dramatic, way to assess the early heat is to consider the number of days at or above 90 degrees this year. Through June 24, we have already had 10 such days this summer — we had a record five such days in May for the first time in Madison’s history. The average number for a summer in Madison is 13, so we are nearly already there. The all-time Madison record for 90-plus days is 39, set in 1955.

You might remember the summers of 1988 and, more recently, 2012 when Madison had a near-record 35 days with a high temperature at or above 90. By June 27, 1988, we had recorded nine such hot days, the full complement for all of June that year. By June 27, 2012 we had only recorded five days at 90 or above, and in 1955, we had had only one — so we are ahead of the paces set in all three of these remarkable years.

July 2012 had 18 days that were that hot, the bulk of those 18 coming in two streaks of six and seven consecutive 90-plus days. If we are to make a run at 30 or more hot days this summer, we will need a couple extended heat waves such as those from 2012. It will be interesting.

Steve Ackerman and Jonathan Martin, professors in the UW-Madison department of atmospheric and oceanic sciences, are guests on WHA radio (970 AM) at 11:45 a.m. the last Monday of each month. Send them your questions at stevea@ssec.wisc.edu or jemarti1@wisc.edu.

Category: Climate, History, Seasons

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