Because of a warming climate, the length of the season for ragweed pollen, a common allergen, increased for many locales across central North America between 1995 and 2015. The one exception was in Austin, Texas, where the length of the season was shortened by one day.

Source: “Climate Change Indicators: Ragweed Pollen Season,” Environmental Protection Agency, August 2016,

Data for the graphic are as follows:

Location Change in Length of Pollen Season
Austin/Georgetown, Texas 1 Day decrease
Oklahoma City, Oklahoma 6 Day increase
Rodgers, Arkansas 11 Day increase
Kansas City, Missouri 25 Day increase
Papillion/Bellevue, Nebraska 15 Day increase
Madison, Wisconsin 15 Day increase
La Crosse, Wisconsin 15 Day increase
Minneapolis, Minnesota 15 Day increase
Fargo, North Dakota 21 Day increase
Winnipeg, Manitoba 25 Day increase
Saskatoon, Saskatchewan 24 Day increase

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