2026 Mosquito Outlook: Are Mosquitoes Worse This Year?

Are Mosquitoes Worse This Year?

Yes. The 2026 US mosquito outlook projects a +10 to 15% increase in mosquito activity compared to the recent baseline, driven by warmer winters allowing larger overwintering populations, the continued northward range expansion of Aedes albopictus and Aedes aegypti, and elevated 2025 surveillance trends across the Plains and California. Peak West Nile Virus transmission is forecast for July 1 - September 30. 8 States (LA, MS, TX, FL, AR, CA, ND, SD carry the highest combined burden by absolute count or per-capita rate) carry the highest combined disease and biting burden.

Sourced from CDC ArboNET surveillance and NOAA climate outlooks. The regional breakdown below shows where in the country the increase concentrates.

2026 Mosquito Forecast: National Overview

The 2026 mosquito activity forecast projects continued elevated WNV transmission across the Plains and California, sustained Gulf South Aedes pressure, and expanded local dengue risk in southern Florida and the Rio Grande Valley. Based on CDC ArboNET surveillance and NOAA climate outlooks.

Projected Activity Increase

+10 to 15%

Forecast mosquito populations based on warming winter temperatures, expanded Aedes aegypti range, and 2025 surveillance trends

Peak WNV Window

July 1 - September 30

Cx. tarsalis and Cx. pipiens transmission peaks in late summer across most of the country

Tier 1 and Tier 2 Pressure

8 States

LA, MS, TX, FL, AR, CA, ND, SD carry the highest combined burden by absolute count or per-capita rate

What to Expect in 2026

The 2026 mosquito season is projected to bring continued elevated activity across most of the country, with the highest pressure on the Gulf South, the Plains, California, and Florida. Climate trends continue to favor expanded Aedes aegypti range, longer biting seasons in the Mid-Atlantic and Southeast, and steady WNV transmission across the Plains and West Coast irrigated agricultural belts. The 2026 mosquito season builds on the post-2013 Aedes aegypti expansion across California and the post-2019 EEE outbreak benchmark in the Northeast.

Climate Factors

Atlantic hurricane landfall years drive post-storm Psorophora and Aedes vexans blooms across the Gulf Coast
Warmer winters extending Aedes albopictus active season 1 to 2 weeks per decade
Western drought variability shifts Cx. tarsalis hot spots year to year in CA, NV, AZ
NOAA climate outlook suggests above-average summer temperatures in the Plains and Upper Midwest

Vector Range Expansion

Aedes aegypti continued northward expansion in CA Central Valley and into the Bay Area
Aedes albopictus expansion north into ME, VT, and NH along the I-95 corridor
Aedes japonicus established across the Northeast and Mid-Atlantic; container-breeding nuisance vector
Recent Caribbean dengue activity keeps local transmission risk elevated in southern FL and the Rio Grande Valley

Geographic Trends

Plains states: continued highest per-capita WNV burden in the country
Florida: year-round Aedes aegypti pressure plus EEE focus areas plus dengue risk
California: heaviest absolute WNV count plus expanding Aedes aegypti urban presence
Hawaii: avian malaria conservation crisis; Wolbachia mosquito suppression program ongoing

Regional Risk Breakdown for 2026

Select your region to see detailed mosquito activity forecasts and recommendations

Northeast

Low to Moderate Risk

States: ME, NH, VT, MA, CT, RI. View detailed state forecasts

2026 Outlook:

Cool maritime climate compresses the season. Cx. pipiens drives WNV transmission across Boston, Hartford, and Providence metros each August. EEE risk concentrated in southeastern Massachusetts (Bristol, Plymouth) Pine Barrens and southern New Hampshire coastal swamps. The 2019-2020 EEE outbreak years remain the regional benchmark; 2026 trends will hinge on Culiseta melanura amplification cycles in cedar swamps.

Primary Vector

Northern House Mosquito (Culex pipiens)

Primary Disease

West Nile Virus and Eastern Equine Encephalitis

Recommendation: Watch CDC ArboNET dashboards from late July through September. Eliminate yard standing water weekly. EEE risk areas: avoid dusk outdoor activity August through September.

Special Note: Aedes albopictus is expanding north along the I-95 corridor as winters soften; daytime suburban biting season is lengthening 1 to 2 weeks per decade.

Check Your Local 2026 Mosquito Risk

Ready to see current mosquito activity in your area? Get today's forecast and personalized risk assessment for your ZIP code.

2026 Monthly Activity Timeline

Click through each month to see activity levels and prevention actions

Very High Activity

August 2026

Peak WNV Window

WNV human transmission peaks across most of the country in August. Cx. pipiens and Cx. tarsalis populations at maximum. EEE transmission risk peaks in the focus areas. Aedes albopictus daytime biting at maximum intensity across the East. Hurricane-driven floodwater Psorophora outbreaks possible across the Gulf Coast.

Recommended Actions:

Watch for symptoms 2 to 15 days after a bite: fever, headache, body aches
Severe headache, neck stiffness, confusion: ER immediately (neuroinvasive WNV or EEE)
EEE focus areas: avoid dusk and dawn outdoor activity through October
Pregnant individuals in southern FL, TX: watch for sporadic dengue advisories

2026 Disease Outlook

West Nile Virus

2024 cases: ~2,500

West Nile Virus

2024 cases: ~2,500

2026 Projection

Stable to slight increase in Plains and CA Central Valley

WNV transmission is climate-sensitive. Warmer summers favor faster Cx. pipiens and Cx. tarsalis development. The Plains states (especially ND, SD, NE) consistently lead per-capita rates. California Central Valley irrigated agriculture sustains the heaviest absolute counts year over year.

Symptoms

About 80% of infections are asymptomatic. Symptomatic cases: fever, headache, body aches, occasional rash. Severe (less than 1%): neuroinvasive disease with meningitis, encephalitis, or paralysis.

Peak Risk Window

July through September across most of the country; year-round risk in southern California and the Gulf Coast.

Prevention

Eliminate standing water around the home weekly. EPA-registered DEET, picaridin, IR3535, or oil of lemon eucalyptus before going outside. Window and door screens with no tears.

Explore Mosquito Forecasts by State

Select your state for a detailed local mosquito forecast and risk assessment.

2026 Mosquito Forecast

The 2026 US mosquito risk outlook: West Nile, EEE, and dengue projections, monthly biting timeline, and regional risk breakdown. Sourced from CDC ArboNET and NOAA climate data.

Are Mosquitoes Worse This Year?

2026 Mosquito Forecast: National Overview

Projected Activity Increase

Peak WNV Window

Tier 1 and Tier 2 Pressure

What to Expect in 2026

Climate Factors

Vector Range Expansion

Geographic Trends

Regional Risk Breakdown for 2026

Northeast

2026 Outlook:

Primary Vector

Primary Disease

Check Your Local 2026 Mosquito Risk

2026 Monthly Activity Timeline

August 2026

Peak WNV Window

Recommended Actions:

West Nile Virus

West Nile Virus

2026 Projection

Symptoms

Peak Risk Window

Prevention

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Yellow Fever Mosquito