Today's Mosquito Risk in Massachusetts: 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 25 confirmed cases annually
- Based on CDC ArboNET surveillance data
- Risk Tier
- Tier 4: Low
- Coastal warming plus EEE focus area drive the highest northeastern risk profile.
- Per mosquito-risk-model regional tier
- Highest-Risk Areas
- Bristol and Plymouth (EEE); Suffolk and Middlesex (WNV)
Current Situation in Massachusetts
Massachusetts sits at the northern edge of the country's most active EEE risk zone. The Bristol-Plymouth pine barrens and southeastern coastal swamps host the Culiseta-Aedes mosquito cycles that drive the state's periodic Eastern Equine Encephalitis outbreaks, a disease with about 30% case fatality. West Nile risk is also present statewide, with Cx. pipiens carrying it through Boston suburbs and the Connecticut Valley each August. Cape Cod, the South Coast, and the Berkshires all see seasonal Aedes albopictus expansion. Massachusetts mosquito season runs late May through early October, with peak biting and disease risk concentrated in August.
Snapshot of the current mosquito situation in Massachusetts, 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 Massachusetts
Massachusetts mosquito habitat is dominated by salt marsh along the North Shore and South Coast, freshwater swamps in Bristol and Plymouth Counties (the EEE focus area), and urban catch-basin Culex breeding throughout the metro. Coastal salt marsh produces the saltmarsh mosquito (Aedes sollicitans). Inland swamps produce Culiseta melanura, the bird-feeding EEE bridge vector. Storm drains and abandoned pools in Boston, Worcester, and Springfield are the main Cx. pipiens sources.
Hotspot Counties & Areas
- Bristol County (EEE focus area)
- Plymouth County (Pine Barrens swamps)
- Suffolk County (Boston metro WNV)
- Cape Cod and the Islands (Aedes activity)
- Connecticut River Valley (agricultural Culex)
- Berkshire County (rural floodwater Aedes)
Seasonal Activity Pattern
Mosquito biting begins in late May once dew points hold above 55 degrees, peaks late July through August, and tapers off after first frost in mid to late October. WNV human cases concentrate in August. EEE cases are rare but when they happen, late August through September is the window. Heavy spring rainfall produces a 1 to 2 week flood-mosquito surge in floodplain areas.
Monthly Biting Intensity (Northeast)
Massachusetts Mosquito Risk Profile
- WNV burden level
- Low
- about 10 to 25 confirmed cases annually
- EEE risk
- High in southeastern Pine Barrens (Bristol, Plymouth)
- Peak biting season
- late May through early October
- Top urban risk areas
- Boston (Suffolk)
- Worcester (Worcester)
- Springfield (Hampden)
- New Bedford (Bristol)
Signature habitat: Pine Barrens cedar swamps (EEE), salt marsh, urban storm drains.
Climate driver: Coastal warming plus EEE focus area drive the highest northeastern risk profile.
Check Your Local Mosquito Risk
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Common Mosquitoes in Massachusetts
Understanding which mosquitoes are active in Massachusetts 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 Massachusetts
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 Massachusetts?
Mosquito activity winds down after the first hard freeze, which in Massachusetts typically arrives around Oct 12. See the local first-frost window and city-by-city freeze dates.
Massachusetts first frost datesAlso worried about ticks in Massachusetts?
Lyme disease risk and tick activity track different seasonal patterns than mosquitoes. See your Massachusetts tick forecast.
View Massachusetts tick forecastStay Safe in Massachusetts
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