Change in the average length of allergy season from 1970 to 2025
Consecutive days above freezing, also known as growing season
A symbol map of U.S. cities showing the change in average allergy season length from 1970 to 2025. For most cities, the season has gotten longer, by an average of 23 days. Reno, Nevada, shows an increase of 100 days, while Tulsa, Oklahoma, has a decrease of 15 days.
