Who likes a warming climate? Northwest mosquitoes

A warming climate has meant better conditions for mosquitoes in much of the Northwest.

A report from the nonprofit Climate Central says mosquito season is now 32 days longer in Seattle than it was 40 years ago.

The season with sufficient warmth and humidity for mosquitoes has grown two weeks longer in Portland and Eugene.

The group analyzed temperature and humidity record at 242 locations in the United States between 1979 and 2022. In nearly three-fourths of the studied locations, mosquito season — with temperatures between 50 and 95 degrees Fahrenheit and relative humidity of at least 42% — increased over that period. In only one-fourth of locations, mostly in the South, where temperatures often exceed 95 degrees, did mosquito season shrink.

“With changing climate, there's winners and losers, and a lot of pest species are winners,” said Aimee Code, who directs the pesticide program at the Portland-based Xerces Society for Invertebrate Conservation. “The warmer the weather, the faster they reproduce.”