Quick Answer
Mosquito season generally starts when temperatures hold consistently around 50°F (usually spring) and ends around the first hard frost, though it runs nearly year-round along the Gulf Coast and much of the Deep South. When it turns cold, most mosquitoes don't actually die — they go dormant. The trigger isn't only temperature: the shortening days of late summer signal certain mosquitoes to prepare for winter. Culex and Anopheles females shelter in protected spots — hollow logs, animal burrows, storm drains, sheds, and basements — entering a hibernation-like state called diapause in which they stop biting and live off stored fat. Aedes mosquitoes (including the Asian tiger mosquito) instead lay cold-hardy eggs that wait out winter and hatch in spring. Male mosquitoes mostly die off with the cold. The practical takeaway: as soon as your local temperatures climb back toward 50°F, mosquitoes start emerging — so the best time to get ahead of them is early, before the population builds.
When does mosquito season start?
There's no single calendar date, because mosquito season tracks temperature, not the month. As a rule of thumb, mosquitoes start becoming active once daytime temperatures hold steady around 50°F, and activity ramps up sharply once it stays above 70°F. In much of the southern U.S. that can mean February or March; across the northern tier it may be late April or May.
What's really happening is that the mosquitoes that spent winter waiting — either as dormant adult females or as eggs — get their cue to resume the life cycle. Warmth rouses the sheltering females, and warmth plus standing water triggers overwintered eggs to hatch. That's why the first warm, wet stretch of spring so often brings the first bites of the year.
When does mosquito season end?
On the back end, the first hard frost is the classic sign that mosquito season is winding down. Once temperatures drop below about 50°F, mosquito activity slows dramatically, and a sustained freeze pushes the survivors into dormancy. Importantly, that first frost doesn't wipe them out — it simply ends the biting season for the year while the next generation waits, hidden, for spring.
In warm-winter regions there may be no true "end" at all: mild spells can keep mosquitoes active into December and beyond, with only brief cold snaps pausing them.
Mosquito season by U.S. region
Because it's temperature-driven, mosquito season looks very different depending on where you live. These are general ranges — your local weather in any given year matters more than the calendar.
| Region | Typical mosquito season | Notes |
|---|---|---|
| Gulf Coast & Deep South (FL, TX, LA) | Nearly year-round | Warm enough for many overlapping generations; only cold snaps pause activity |
| Southeast, Mid-Atlantic, Southern Plains | ~March–October | Long, humid season with multiple broods |
| Midwest, Northeast, Pacific Northwest | ~Late April/May–September | Peaks in mid-summer |
| Northern tier & high elevation | ~June–August | Short but intense; often fewer generations |
Wherever you are, the 50°F threshold is the practical signal: when your area crosses it in spring, mosquitoes are on the way.
The life cycle behind the season
To understand why season length varies so much, it helps to know how fast mosquitoes actually reproduce. All mosquitoes go through four stages — egg, larva, pupa, adult — and the first three happen in standing water. That's the whole reason source reduction works, and it's covered in our guide on where mosquitoes lay their eggs.
The pace is what surprises people. In warm conditions, a mosquito can go from egg to biting adult in about 7 to 14 days — sometimes as fast as 4 days, and as slow as a month when it's cool. The aquatic larvae (nicknamed "wigglers") spend roughly 4 to 14 days in the water depending on temperature, and the pupae ("tumblers") only 1 to 4 days before the adult emerges.
Because each cycle is so short, warmth doesn't just lengthen the season on the calendar — it stacks up generations. In the coldest regions, some species manage just one generation per year; in warm regions, mosquitoes can run through many overlapping broods (in parts of the country, four or more), which is exactly why a Gulf Coast summer feels relentless while a northern one comes in a shorter, sharper burst. It's also why getting control in place early matters so much: every generation you prevent in spring is several you don't fight later.
Do mosquitoes die in winter?
Mostly, no. It's a common assumption that a cold snap kills all the mosquitoes, but the species that plague U.S. yards have spent millions of years learning to survive winter. Male mosquitoes — which don't bite and live only a short time — largely do die off as it cools. But the biting females, and the next generation waiting as eggs, are built to persist. Instead of dying, they shut down and wait.
This is why mosquitoes can seem to "reappear" almost overnight in spring: they were never really gone, just dormant nearby. (For a bigger-picture look at what mosquitoes are actually for, see our piece on what would happen if mosquitoes disappeared.)
Where do mosquitoes go in winter?
Here's the part most guides skip: the switch into winter mode is triggered as much by day length as by cold. As late-summer days shorten, that shrinking photoperiod — sensed while the mosquito is still developing as a larva or pupa — programs the next generation of females for diapause, a hibernation-like state of suspended reproduction and slowed metabolism. Research on the northern house mosquito (Culex pipiens) has documented females beginning to appear in overwintering shelters as early as August, well before the first frost.
Those diapause-bound females also undergo a striking behavioral flip. Instead of seeking blood, they switch to what researchers have described as "sugar gluttony" — feeding heavily on nectar and rotting fruit to pack on fat reserves that will fuel them through months of dormancy. In other words, they stop biting you and start fattening up. Where and how they wait out winter depends on the species:
- Adult females (Culex, Anopheles): Mated, fat-loaded females tuck into cool, humid, sheltered places — hollow logs, animal burrows, culverts and storm drains, woodpiles, plus human structures like sheds, garages, crawl spaces, and basements — and simply wait out the cold.
- Eggs (Aedes, including the Asian tiger mosquito): Rather than overwinter as adults, these species lay tough, desiccation-resistant eggs in dry areas that tend to flood later. The eggs enter their own dormancy and hatch when spring brings warmth and standing water.
- Males: Generally short-lived, they die off with the onset of cold weather and are replaced by the next generation in spring.
According to the American Mosquito Control Association, this overwintering ability is exactly why source reduction matters so much: the sheltered adults and hidden eggs around your property in fall become next spring's first wave.
Why mosquitoes seem to vanish before winter
That late-summer "sugar gluttony" switch explains something you've probably noticed: the biting often eases off in early fall even while you still see mosquitoes around. Once diapause-destined females stop host-seeking, they're no longer interested in you — they're focused on nectar and finding shelter. The population hasn't crashed yet; it's changing behavior. It's a useful reminder that "fewer bites" in September doesn't mean the mosquitoes are gone, and that fall is actually the smartest time to disrupt the ones setting up for next year.
What time of day are mosquitoes most active during the season?
Within the active season, mosquitoes aren't equally busy all day. Most species peak at dawn and dusk, when the air is cooler and more humid, and back off during the hot, dry middle of the day (though shady, humid yards can stay buggy around the clock). If you're specifically fighting bites after dark, we go deeper in our guide on getting rid of mosquitoes at night.
Is mosquito season getting longer?
In many parts of the country, yes. Because the season is bounded by temperature, warmer springs and later first-frosts stretch the window on both ends — and, as we saw above, more warm days can mean more generations packed into a year. For homeowners, the practical effect is simply that the period when active control is worthwhile now starts earlier and can run later than it used to — another reason to watch local temperatures rather than the calendar.
Your month-by-month mosquito control calendar
Because the season is a rhythm, control works best as a routine rather than a mid-summer scramble. Here's a simple seasonal framework you can adapt to your local climate — shift it earlier in the South and later up North.
| Phase | What's happening | What to do |
|---|---|---|
| Early spring (temps nearing 50°F) | Overwintered females wake; first eggs hatch | Do a standing-water walkthrough; set out traps now to catch the first wave before it breeds |
| Late spring | First generations emerge and start biting | Empty/refresh anything holding water weekly; keep traps running |
| Summer (peak) | Multiple overlapping generations | Stay consistent — drain water after every rain, maintain traps, focus on dawn/dusk protection |
| Late summer (days shortening) | Diapause-bound females begin fattening up and sheltering | Don't quit early — disrupting them now reduces next year's starters |
| Fall (around first frost) | Biting eases; females hide, eggs are laid | Do a fall cleanup of overwintering sites (below); wind down active trapping |
| Winter | Dormancy | Off-season: repair screens, plan next year's source reduction |
Get ahead of next year: fall overwintering cleanup
The single most under-used move in mosquito control is the fall cleanup, because it targets the females and eggs that start next season. As mosquitoes settle in for winter, work through this checklist around your property:
- Dump and store standing water before it freezes — buckets, saucers, tarps, toys, wheelbarrows.
- Clear clogged gutters and leaf-choked drains where water pools.
- Remove leaf litter and tidy woodpiles near the house, which give sheltering females cover.
- Seal or ventilate sheds, garages, crawl spaces, and basements where adult females overwinter — and check window wells and storm drains nearby.
- Note the Aedes trouble spots: dry low areas that flood in spring are exactly where cold-hardy eggs wait, so improving drainage now pays off in April.
Our mosquito-proof-your-yard guide walks through year-round source reduction in more detail.
When to start (and stop) mosquito control
The best time to act is early — right as your local temperatures approach that 50°F mark and the first mosquitoes emerge, before the population has a chance to multiply. As the season starts, setting out a CO₂-based trap like Mosquito TNT works with the same signal mosquitoes use to find you: a five-ingredient bait releases carbon dioxide for up to 30 days, and host-seeking females drawn toward that CO₂ are captured in the jar. It runs with no electricity or propane and is safe to use around kids and pets when used as directed.
Full transparency: Mosquito TNT is our own product, so we're biased — but the timing principle holds no matter what you use. Start early, stay consistent through your local season, and you can ease off as the first frosts arrive. If you're weighing options, compare formats in our breakdown of mosquito traps by type or our roundup of the best mosquito trap for a yard. And if you're counting on backyard wildlife to handle it, our look at the natural predators of mosquitoes explains why they help but rarely solve the problem.
Frequently Asked Questions
What temperature is too cold for mosquitoes?
Mosquitoes become sluggish below about 60°F and largely stop flying and biting below 50°F. At those temperatures they don't die — they enter dormancy (diapause) and wait for warmth to return. Sustained freezes end the active biting season, but the females sheltering in protected spots and the cold-hardy eggs laid in fall survive to restart the cycle in spring. The 50°F mark is the most useful practical threshold for both the start and end of mosquito season.
Where do mosquitoes go in the winter?
It depends on the species. Culex and Anopheles females overwinter as adults, sheltering in cool, humid, protected places such as hollow logs, animal burrows, storm drains, culverts, woodpiles, sheds, garages, and basements, where they enter diapause. Aedes species, including the Asian tiger mosquito, instead overwinter as tough, cold-resistant eggs laid in dry areas prone to flooding, which hatch when spring warmth and water arrive. Male mosquitoes generally die off with the cold rather than overwintering.
Why do mosquitoes stop biting in the fall?
As late-summer days shorten, females destined to overwinter switch out of blood-feeding mode. Instead of seeking hosts, they feed on nectar and rotting fruit to build up fat reserves for dormancy — a shift researchers have called "sugar gluttony." So the drop in bites you notice in early fall is partly a behavior change, not just a population crash: the mosquitoes are still around, but the overwintering females simply aren't interested in biting anymore. This is why fall is a smart time to disrupt overwintering sites.
How many generations of mosquitoes are there in a year?
It varies enormously by climate and species. In the coldest regions, some mosquitoes complete just one generation per year (they're called "univoltine"). In warm regions with a long season, mosquitoes are "multivoltine" and can run through many overlapping generations — in parts of the country, four or more broods a year. Because a single generation can take as little as 7 to 14 days in warm weather, heat effectively multiplies the mosquito population over a season, which is why warm, humid climates have such persistent mosquito pressure.
Do mosquitoes come back every year?
Yes. Because overwintering females and dormant eggs survive the cold locally, mosquitoes return each spring as temperatures climb back toward 50°F. They don't have to travel far or be "reintroduced" — the next generation is usually waiting right around your property. That's why eliminating standing water and overwintering habitat in fall, and getting control in place early in spring, both make a real difference.
When does mosquito season start and end?
Mosquito season starts when temperatures hold steadily around 50°F and accelerates above 70°F, which can mean anywhere from February in the Deep South to May in northern states. It ends around the first hard frost, when a sustained drop below 50°F pushes mosquitoes into dormancy. In warm-winter regions like the Gulf Coast, the season can run nearly year-round with only brief pauses during cold snaps. Watch your local temperatures rather than a fixed date.
Does a frost kill all the mosquitoes?
No. A first frost ends the active biting season and kills off many of the short-lived males, but it does not eliminate the population. The females that will start next year's generation move into sheltered spots and go dormant, and cold-hardy eggs sit dormant in the soil and leaf litter. This is why mosquitoes reliably return the following spring even after a hard winter.
When should I start using a mosquito trap?
Start as your local season begins — when temperatures approach 50°F and the first mosquitoes appear — rather than waiting for peak summer. Getting control in place early, before the population multiplies, makes the whole season easier to manage. Pair a trap with removing standing water, and keep it going consistently through your area's active months. You can wind down as the first frosts arrive and mosquitoes head into dormancy.
The bottom line on mosquito season
Mosquito season isn't a date on the calendar — it's a temperature-and-daylight window that opens around 50°F in spring and closes with the first hard frost, stretching nearly year-round in the warmest regions. Winter doesn't defeat mosquitoes; it just hides them, as fat-loaded dormant females in sheltered spots and cold-hardy eggs waiting for spring. The most effective response is to work with that rhythm: clear out standing water and overwintering habitat, then get control in place early as temperatures rise — and don't quit too soon in late summer, when next year's mosquitoes are already getting ready. If you'd like a simple way to target the season's first wave, take a look at Mosquito TNT — and reclaim your yard before the bites begin.
Sources
- American Mosquito Control Association (AMCA) — Mosquito Life Cycle & Biology. mosquito.org
- Rutgers Center for Vector Biology — General Mosquito Biology & life-cycle classification. vectorbio.rutgers.edu
- U.S. Environmental Protection Agency (EPA) — Mosquito Life Cycle. epa.gov
- U.S. Army — "Where Do Mosquitoes Go During The Winter?" army.mil