Today's Mosquito Risk in New Hampshire: 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 3 to 8 confirmed cases annually
- Based on CDC ArboNET surveillance data
- Risk Tier
- Tier 4: Low
- EEE risk concentrated in southeastern coastal swamp areas.
- Per mosquito-risk-model regional tier
- Highest-Risk Areas
- Rockingham and Strafford (EEE); Hillsborough (WNV)
Current Situation in New Hampshire
New Hampshire runs cool and forested, with mosquito risk concentrated in the southeastern coastal swamps and the Lake Winnipesaukee basin. WNV burden stays minimal at roughly 3 to 8 confirmed human cases annually, but EEE is the more serious worry: documented outbreaks in 2019 and 2020 produced fatalities tied to the freshwater swamps of Rockingham and southern Strafford counties. The White Mountains stay mostly free of arboviral pressure, though their summer Aedes hatches are legendary on the trail. Culex pipiens dominates the urban biting load in Manchester and Nashua. Biting season runs June through September, with EEE concern peaking late August into September.
Snapshot of the current mosquito situation in New Hampshire, drawn from CDC ArboNET surveillance and the regional risk model.
- Risk Level
- Minimal
- Peak Activity
- June through September
- Dominant Vector
- Northern House Mosquito (Culex pipiens)
Where Mosquitoes Breed in New Hampshire
New Hampshire's most consequential mosquito habitat is the cluster of red maple and Atlantic white cedar swamps in Rockingham County, including Pawtuckaway State Park and the wetlands feeding Great Bay estuary. These produce Culiseta melanura, the bird-feeding bridge vector that drives EEE amplification in late summer. Seacoast salt marsh in Hampton and Seabrook produces Aedes sollicitans. Inland, beaver ponds and forested swamps across the White Mountains and Lakes Region produce big floodwater Aedes hatches. Storm drains in Manchester, Nashua, and Concord carry the urban Cx. pipiens load.
Hotspot Counties & Areas
- Rockingham County (EEE focus area, coastal swamps)
- Hillsborough County (Manchester and Nashua metros)
- Strafford County (Durham, Dover, Great Bay wetlands)
- Merrimack County (Concord, central swamps)
- Pawtuckaway State Park area
- Lake Winnipesaukee shoreline
- White Mountain National Forest trails
Seasonal Activity Pattern
Biting starts in early June, peaks in late July through August, and tapers by late September. EEE risk is concentrated in the late August through September window in the southeastern swamp counties. WNV cases land in August in the Manchester and Nashua metros. Heavy June rainfall produces brief floodwater Aedes surges that drive complaint calls but carry minimal disease risk. The White Mountains run 1 to 2 weeks behind the seacoast on phenology.
Monthly Biting Intensity (Northeast)
New Hampshire Mosquito Risk Profile
- WNV burden level
- Minimal
- about 3 to 8 confirmed cases annually
- EEE risk
- Documented EEE outbreaks in 2019 and 2020
- Peak biting season
- June through September
- Top urban risk areas
- Manchester (Hillsborough)
- Nashua (Hillsborough)
- Concord (Merrimack)
Signature habitat: forested swamps, coastal salt marsh, alpine snow-pool.
Climate driver: EEE risk concentrated in southeastern coastal swamp areas.
Check Your Local Mosquito Risk
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Common Mosquitoes in New Hampshire
Understanding which mosquitoes are active in New Hampshire 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 New Hampshire
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.
Heading to a lake in New Hampshire?
Live water temperatures and swim conditions for Lake Winnipesaukee, Lake Umbagog, Squam Lake, and 4 more.
See New Hampshire lake temperaturesWhen does mosquito season end in New Hampshire?
Mosquito activity winds down after the first hard freeze, which in New Hampshire typically arrives around Sep 25. See the local first-frost window and city-by-city freeze dates.
New Hampshire first frost datesAlso worried about ticks in New Hampshire?
Lyme disease risk and tick activity track different seasonal patterns than mosquitoes. See your New Hampshire tick forecast.
View New Hampshire tick forecastStay Safe in New Hampshire
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