With only a few exceptions, it seems as if this year’s run-up to summer, which arrived at 3:24 a.m. Sunday, June 21, was relatively mild. By that we mean very few really oppressively hot and humid days.
Naturally, we wondered if this were actually a true impression and also how this year’s spring stacked up against others that have visited Madison over the years. One way (but not the only way) to make such an assessment is to consider how many days in the interval from April 1 to June 21 have had a daily high temperature greater than or equal to 80 degrees Fahrenheit.
For 2026, that number is 15 or about once every 5.5 days. Using records all the way back to 1869, the average number of such days in that calendar interval is 13.7 (once every six days), so this year is just barely above that long term average. Interesting individual years according to this measure are 1878 when not a single day between April 1 and June 21 was 80 degrees in Madison. On the other extreme, in 1991 there were 36 such days in the same interval — almost every other day!
Because this measure is highly variable from year to year, looking at decade averages can lend more insight into trends that might exist in this data. The coldest decades were the 1900s and the 1870s with 8.4 and 8.9 such days on average each year. The warmest decades were the 1970s and 1950s with 19.5 and 18.9 such days per year on average. The 2010s, averaged 16.7 such days each year.
With 15 days at 80 degrees or warmer, this year is the 94th coldest spring of the last 158 springs, decidedly on the warm side of the distribution.
However, there appears to be no correlation between number of days at or above 80 degrees during spring and the severity of summer heat, so we will have to wait and see on that.
Steve Ackerman and Jonathan Martin, professors in the UWMadison department of atmospheric and oceanic sciences, are guests on Wisconsin Public radio at noon the last Monday of each month. send them your questions at stevea@ssec.wisc.edu or jemarti1@wisc.edu.
