With Memorial Day and the unofficial summer vacation season just around the corner, summer heat will soon begin to settle in. After a phenomenally warm February for much of the country, many of you have been asking us to take a look at how much earlier in the year the first occurrence of summer-like high temperatures are arriving.
This week, we examine how early in the year certain threshold high temperatures first occurred in our Climate Matters markets. While we found a large variation from place to place, the vast majority of our stations analyzed (78%) had the first occurrence of a threshold high temperature trending earlier in the year. Some of the strongest trends were found in California, Florida, and the Great Lakes. Compared to 1970:
- San Diego and San Francisco are seeing their first occurrence of 80°F about a month earlier.
- Orlando and Tampa are seeing their first occurrence of 90°F about a week earlier. Miami’s first occurrence of 90°F is about a month earlier.
- Detroit, Erie, Grand Rapids, Milwaukee, and Saginaw are all seeing their first occurrence of 80°F about 2-3 weeks earlier.
There are a handful of places, generally in the Carolinas and Georgia, where the first occurrence of 90°F is actually coming about 1-2 weeks later.
To determine each market’s threshold temperature, we examined the frequency of maximum temperatures, in increments of 10°F, between 70-110°F, for each market.
The threshold temperature for each market was chosen at the highest of these increments occurring at least 15 times per year. If you have another threshold temperature in mind that resonates with your market, let us know, and we can perform the analysis at that temperature.