Today's Mosquito Risk in Connecticut: Real-Time Forecast & Activity Map
Check your ZIP code for local mosquito activity, West Nile risk, and prevention insights.
Built from CDC and NOAA data
Mosquito Surveillance Insights
- Annual WNV Cases
- about 10 to 20 confirmed cases annually
- Based on CDC ArboNET surveillance data
- Risk Tier
- Tier 4: Low
- Connecticut River corridor and coastal towns warm enough for albopictus.
- Per mosquito-risk-model regional tier
- Highest-Risk Areas
- Fairfield and New Haven (WNV); New London (EEE)
Current Situation in Connecticut
Connecticut runs warmer and wetter than its northern neighbors, with mosquito pressure built around the Connecticut River floodplain and the Long Island Sound salt marsh. WNV burden lands in the low range at roughly 10 to 20 confirmed human cases annually, with most concentrated in Fairfield and New Haven counties along the densely populated coast. EEE is documented at the southeast coast in New London County, where freshwater swamps near Devil's Hopyard State Park produce periodic Culiseta melanura activity. Aedes albopictus is established statewide and dominates daytime suburban biting. Mosquito season runs June through September, peaking in August.
Snapshot of the current mosquito situation in Connecticut, drawn from CDC ArboNET surveillance and the regional risk model.
- Risk Level
- Low
- Peak Activity
- June through September
- Dominant Vector
- Northern House Mosquito (Culex pipiens)
Where Mosquitoes Breed in Connecticut
Connecticut mosquito habitat splits between the tidal salt marsh of Long Island Sound, the Connecticut River floodplain running north through Hartford, and the suburban storm drains threading every metro. Coastal marshes from Stamford through Old Saybrook produce Aedes sollicitans and Culex salinarius. The Pequonnock River wetlands and the lower Connecticut River bottomlands sustain dense Cx. pipiens populations. Inland forested swamps in eastern New London and Windham counties produce the EEE bridge vector. Catch basins and tire piles across Bridgeport, New Haven, and Hartford carry urban Aedes albopictus.
Hotspot Counties & Areas
- Fairfield County (suburban WNV, dense Aedes albopictus)
- New Haven County (coastal salt marsh, urban Culex)
- Hartford County (Connecticut River floodplain)
- New London County (EEE focus area, southeast coast)
- Connecticut River Valley
- Long Island Sound shoreline
- Devil's Hopyard State Park area (East Haddam)
Seasonal Activity Pattern
Biting starts in early June, peaks late July through August, and tapers through September. WNV cases concentrate in August in the Fairfield-New Haven corridor and the Hartford metro. EEE risk lands in late August through September in the southeastern swamp counties. Aedes albopictus daytime biting in suburban yards stays heavy from July through early October. Heavy summer storms produce 1 to 2 week floodwater Aedes pulses across the Connecticut River bottomlands.
Monthly Biting Intensity (Northeast)
Connecticut Mosquito Risk Profile
- WNV burden level
- Low
- about 10 to 20 confirmed cases annually
- EEE risk
- Documented at southeast coast
- Peak biting season
- June through September
- Top urban risk areas
- Hartford (Hartford)
- Bridgeport (Fairfield)
- New Haven (New Haven)
Signature habitat: Connecticut River floodplain, Long Island Sound salt marsh, suburban Culex.
Climate driver: Connecticut River corridor and coastal towns warm enough for albopictus.
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Common Mosquitoes in Connecticut
Understanding which mosquitoes are active in Connecticut helps you identify threats and take appropriate precautions. Click any card for details.
Northern House Mosquito
Culex pipiens
Risk: West Nile virus, St. Louis encephalitis, dog heartworm.
Key feature: Medium brown body with banded abdomen. Looks nearly identical to Cx. quinquefasciatus.
Active: Late spring through early fall in the north. Adult females overwinter in basements, garages, and storm drains.
Inland Floodwater Mosquito
Aedes vexans
Risk: Aggressive nuisance biter. Weak vector for West Nile, dog heartworm.
Key feature: Brown body with pale bands on the legs and a tapered abdomen.
Active: Spring through fall. Population spikes a week or two after major rain events.
Asian Tiger Mosquito
Aedes albopictus
Risk: Eastern Equine Encephalitis, dengue, chikungunya, Zika, dog heartworm.
Key feature: A single bright white stripe down the center of the back.
Active: Spring through first hard frost. Eggs overwinter in cold climates and hatch when flooded by spring rain.
West Nile Virus
Vector: Northern House Mosquito
West Nile Virus
The dominant West Nile vector across the northern half of the US. About 80% of infections are asymptomatic.
What to watch for
- Onset typically 2 to 15 days after a bite
- Most cases mild or asymptomatic, small fraction severe
- Neurological signs (severe headache, neck stiffness, confusion) need ER care
Breaking the Cycle in Connecticut
The mosquito lifecycle takes about a week. These habits cut local biting pressure faster than anything else, building multiple layers of protection.
Drain the Yard Weekly
Empty buckets, planter saucers, kiddie pools, tarps, and clogged gutters. A week of standing water is one full mosquito generation.
Repel Before Going Out
EPA-registered DEET (20-30%), picaridin (20%), IR3535, or oil of lemon eucalyptus. Apply before going outside, especially at dusk and dawn.
Seal the House
Window and door screens with no tears. AC and porch fans both work. Mosquitoes struggle to fly upwind even at 1-2 mph air speed.
Treat Outdoor Clothing
Permethrin-treated long sleeves and pants for evening yard work, hiking, or fishing. Remains effective through 70+ wash cycles.
If You Develop Symptoms
Most mosquito bites are harmless. A small fraction can transmit illness, and knowing the timeline matters more than panicking at every itch.Five things to know.
Watch for fever
Fever, body aches, headache, or fatigue 2 to 15 days after a bite. West Nile often feels like flu, and most infections never get diagnosed.
Note where and when
A rough record of where and when you got bitten helps your doctor decide what to test for. Date, location, mosquito-heavy areas you visited.
Get help fast for neuro signs
Severe headache, neck stiffness, confusion, vision changes, or sudden muscle weakness can mean neuroinvasive WNV or EEE. Both are medical emergencies.
Pregnant exposure?
If pregnant and bitten in an area with documented Zika or local dengue transmission, mention to your OB. Same goes for travel exposure.
Children and seniors
Higher risk of severe disease from WNV, EEE, and dengue in adults over 60 and children under 5. Early call to the pediatrician or PCP if symptoms appear.
When does mosquito season end in Connecticut?
Mosquito activity winds down after the first hard freeze, which in Connecticut typically arrives around Oct 14. See the local first-frost window and city-by-city freeze dates.
Connecticut first frost datesAlso worried about ticks in Connecticut?
Lyme disease risk and tick activity track different seasonal patterns than mosquitoes. See your Connecticut tick forecast.
View Connecticut tick forecastStay Safe in Connecticut
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