Mosquito season is longer and spreading north

Climate change is extending mosquito season across North America and pushing disease-carrying species into places they never used to survive.

Warmer temperatures are the main driver. Mosquitoes are cold-blooded, so they thrive in heat. Milder winters mean more adults survive the cold months, and spring arrives earlier, so breeding starts sooner. In many parts of the U.S. and Canada, the mosquito “season” now starts weeks earlier and ends weeks later than it did 30 years ago.

That’s not just annoying — it’s a real public health shift. The mosquitoes that carry West Nile, dengue, and even malaria are moving north. The Asian tiger mosquito (the aggressive daytime biter) has established itself as far north as New England and the Great Lakes, which it couldn’t do a few decades ago. Warmer