Today's Mosquito Risk in North Dakota: 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 50 to 100 confirmed cases annually
- roughly 11 per 100k cumulative incidence (highest in country)
- Based on CDC ArboNET surveillance data
- Risk Tier
- Tier 2: High Pressure
- Highest per-capita WNV burden in the country; pothole prairie produces enormous Cx. tarsalis populations July through August.
- Per mosquito-risk-model regional tier
- Highest-Risk Areas
- Cass, Burleigh, Grand Forks, Ward (metros); Red River Valley and Missouri Coteau counties (Cx. tarsalis)
Current Situation in North Dakota
North Dakota carries the highest per-capita WNV burden in the country at roughly 11 cases per 100,000 cumulative incidence, with about 50 to 100 confirmed human cases annually distributed across the Fargo, Bismarck, Grand Forks, and Minot metros and the prairie pothole counties of the central and eastern tier. The small population masks the scale of exposure. The state sits in the Plains Cx. tarsalis regime, and the agricultural Culex is the dominant WNV transmission vector across the Red River Valley and the Missouri Coteau pothole prairie. The biting season is brutal but short, with explosive Aedes vexans hatches off spring snowmelt across the prairie pothole region in May and June. Aedes albopictus is rare. EEE is rare. The Pembina Hills hold cooler woodland habitat. Biting season runs late May through September, peaking late July through August.
Snapshot of the current mosquito situation in North Dakota, drawn from CDC ArboNET surveillance and the regional risk model.
- Risk Level
- Moderate
- Peak Activity
- June through September
- Dominant Vector
- Western Encephalitis Mosquito (Culex tarsalis) statewide and dominant WNV vector
Where Mosquitoes Breed in North Dakota
North Dakota mosquito habitat is built on the Red River Valley and the Missouri Coteau pothole prairie. The Red River Valley along the Minnesota border from Fargo through Grand Forks holds flat lake-bed soils that drain slowly and produce massive Aedes vexans hatches off snowmelt and dense summer Cx. tarsalis populations off the irrigated farm grid. The Missouri Coteau across the central counties holds glacial pothole prairie with thousands of small wetlands sustaining steady summer Cx. tarsalis and Aedes vexans. Devils Lake sits as a closed-basin lake with extensive shoreline marsh, and Lake Sakakawea on the Missouri River carries seasonal floodwater pulses. The Souris River, also called the Mouse River, runs through Minot and produces heavy Aedes vexans floods after spring runoff. J. Clark Salyer and Tewaukon National Wildlife Refuges hold dense pothole prairie habitat. Theodore Roosevelt National Park in the western badlands runs drier with lower pressure.
Hotspot Counties & Areas
- Cass County (Fargo, Red River Valley)
- Burleigh County (Bismarck, Missouri River)
- Grand Forks County (Grand Forks, Red River)
- Ward County (Minot, Souris River)
- Devils Lake (Ramsey County)
- Lake Sakakawea (Missouri River)
- J. Clark Salyer National Wildlife Refuge
- Theodore Roosevelt National Park (badlands)
Seasonal Activity Pattern
Biting starts in late May across the Red River Valley and the eastern pothole counties off snowmelt, peaks late July through August, and tapers fast through September with the first frost. WNV cases concentrate in August across the Red River Valley and the Missouri Coteau and the Fargo, Bismarck, and Grand Forks metros. Spring snowmelt off the prairie pothole region produces explosive Aedes vexans hatches from late May through June, with dense biting across field and river-bank counties. Cx. tarsalis populations build through July with the irrigation cycle and stay elevated through August. The compressed summer season produces some of the most intense biting in the country for a 6 to 8 week window.
Monthly Biting Intensity (Plains)
North Dakota Mosquito Risk Profile
- WNV burden level
- Moderate
- about 50 to 100 confirmed cases annually; roughly 11 per 100k cumulative incidence (highest in country)
- EEE risk
- Rare
- Peak biting season
- June through September
- Top urban risk areas
- Fargo (Cass)
- Bismarck (Burleigh)
- Grand Forks (Grand Forks)
Signature habitat: Red River Valley, Missouri Coteau pothole prairie, Devils Lake wetlands.
Climate driver: Highest per-capita WNV burden in the country; pothole prairie produces enormous Cx. tarsalis populations July through August.
Check Your Local Mosquito Risk
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Common Mosquitoes in North Dakota
Understanding which mosquitoes are active in North Dakota 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.
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 North Dakota
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 North Dakota?
Mosquito activity winds down after the first hard freeze, which in North Dakota typically arrives around Sep 22. See the local first-frost window and city-by-city freeze dates.
North Dakota first frost datesAlso worried about ticks in North Dakota?
Lyme disease risk and tick activity track different seasonal patterns than mosquitoes. See your North Dakota tick forecast.
View North Dakota tick forecastStay Safe in North Dakota
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