It's Not Cold Enough Yet The most straightforward reason mosquitos are still around in October is that it isn't cold enough to kill them yet. Just as ticks become dormant when the temperatures drop to 40 degrees, mosquitos will remain a threat until 50 degrees.

You are still seeing mosquitoes in October primarily because of unseasonably warm late-season weather and the specific biology of "fall" mosquitoes. Mosquitoes do not simply disappear when the calendar flips to autumn; they remain active as long as the temperature stays consistently above 10°C (50°F). In many regions, mild Octobers with lingering humidity and late-season rains provide perfect breeding grounds in damp leaf piles, clogged gutters, or undrained flower pots. Furthermore, female mosquitoes become more aggressive in the fall as they seek a final "blood meal" to provide the nutrients necessary for them to survive the winter or to lay a final batch of eggs that will hatch in the spring. If your area hasn't experienced a "hard frost" (several hours of sub-freezing temperatures), the local mosquito population will continue to thrive, particularly during the day, which is an interesting shift from their typical summer dusk-to-dawn activity.