Minnesota’s mosquito season a month longer due to climate change

It's been mockingly called Minnesota's state bird.

Minnesotans know mosquitoes are a fact of life in summer. Thanks to climate change, mosquito season in Minnesota is now more than a month longer since 1980, according to a new study by Climate Central.

Climate Central

The Climate Central report analyzes the number of days with ideal temperature and humidity for mosquitoes since 1980 across the U.S.. The study includes the 200 largest cities in the U.S., and Minneapolis-St. Paul ranks 3rd highest for the increased number of ideal mosquito days in the nation.

Mosquito cities
Climate Central

Fits with longer term trends

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The notion of longer a mosquito season fits with the observed increase in longer frost-free season we have observed in Minnesota in the past 40 years. The study finds that ideal 'weather mosquito days' in the Twin Cities have increased by 34 days per year on average since the 1980s.

Mosquito days increase
Climate Central

Climate Central elaborates on the methodology in the new study.

Climate Central’s States at Risk project has analyzed how the length of the mosquito season has been changing across hundreds of metropolitan areas across the Lower 48 states. We found that in most of the country, rising temperatures and humidity since the 1980s have driven an increase in the number of days each year with ideal conditions for mosquitoes. Warming temperatures lead to more evaporation, which puts more water vapor in the atmosphere and increases humidity. The overall increase in mosquito days in the U.S. is likely increasing the risk of several mosquito-borne diseases, including the Zika virus.

Climate Central analyzed how the number of days each year with ideal conditions for mosquitoes has been changing since 1980. We found that most major cities in the country (76 percent) have seen an overall increase in days conducive for mosquitoes in the past 36 years, and many regions have seen the mosquito season increase by half a month or more.

Among the 200 largest metro areas in the U.S., 10 cities have seen their seasons grow by a month or more over this relatively short period of time. Overall, 125 cities are now seeing their average annual mosquito seasons at least five days longer than they were in the 1980s.

The study has implications on how new diseases like West Nile and Zika virus may expand into Minnesota as our climate continues to warm.