The question of whether mosquitoes are still active in November has a highly variable answer that depends almost entirely on local climate conditions. For many regions, November marks a transition where insect activity slows dramatically, but it does not guarantee their complete disappearance. The shift from active feeding and breeding to dormancy is triggered by environmental cues, making mosquito persistence a matter of geography and temperature, rather than a fixed date on the calendar.
How Mosquitoes Survive Cold Weather
Mosquitoes are cold-blooded insects, meaning their internal temperature and activity levels are directly linked to the external environment. They have evolved biological mechanisms to survive seasonal cooling, avoiding death from freezing. The primary survival strategy is a state of arrested development called diapause, similar to hibernation in mammals. This metabolic slowdown allows them to conserve energy and wait out unfavorable conditions, such as cold or drought.
Different species utilize different life stages for overwintering during diapause. Many common species, such as Aedes mosquitoes, survive the cold as hardy, drought-resistant eggs laid in areas that will flood when warm weather returns. Other species, including some in the Culex genus, survive as mated adult females. These females seek sheltered spots like basements or culverts, remaining in stasis until spring.
The Critical Temperature for Inactivity
The most important factor determining the end of the mosquito season is sustained temperature. Most mosquito species become inactive and stop flying when ambient temperatures consistently drop below 50°F (10°C). Below this threshold, their ability to metabolize and seek blood meals is significantly reduced, prompting them to enter diapause.
A single cold night is not enough to end the season if daytime temperatures consistently rebound above 50°F. The shift requires a pattern of sustained cold, especially at night, to halt activity across the population. While freezing temperatures below 32°F kill most exposed adult mosquitoes, their eggs and dormant adult females can survive harsh winters in sheltered locations.
Regional Differences in November Mosquito Activity
Applying the temperature principle reveals why November activity is inconsistent across different areas. In northern regions, such as the Northeast and upper Midwest, the mosquito season typically concludes by mid-to-late October as sustained temperatures fall below the 50°F threshold. These areas usually experience a respite once a hard freeze occurs.
In warmer regions, however, the season often extends well into November, and sometimes year-round. States along the Gulf Coast, in the Deep South, and coastal California frequently experience daytime temperatures warm enough for mosquitoes to fly, feed, and breed. In these areas, mosquitoes may simply slow their pace rather than entering full diapause, sometimes lasting nearly year-round in tropical climates.
Protecting Yourself If Mosquitoes Linger
In regions where November temperatures remain mild, continued vigilance is necessary to reduce the risk of bites and disease transmission, such as West Nile Virus. The most direct form of prevention involves eliminating standing water, which is the only environment where mosquitoes can lay eggs and larvae can develop. Even small amounts of water can serve as breeding sites, persisting longer because colder weather slows evaporation.
Personal protection should continue with the use of EPA-approved insect repellents on exposed skin. During warmer spells, ensuring that window and door screens are intact prevents lingering adult females from seeking shelter indoors, such as in basements or garages, to overwinter. Trimming back overgrown vegetation also helps, as dense foliage provides resting spots for adults.