Today's Mosquito Risk in Wyoming: 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 5 to 20 confirmed cases annually
- low absolute count, high per-capita
- Based on CDC ArboNET surveillance data
- Risk Tier
- Tier 5: Minimal
- Borderline tier placement; high per-capita WNV but tiny population means single-digit total cases most years.
- Per mosquito-risk-model regional tier
- Highest-Risk Areas
- Natrona, Laramie, Albany (metros); North Platte corridor and Bighorn Basin counties (Cx. tarsalis)
Current Situation in Wyoming
Wyoming carries a low absolute WNV burden of roughly 5 to 20 confirmed human cases annually, but the tiny population pushes per-capita exposure higher than the raw count suggests. Risk concentrates along the North Platte River corridor through Casper and across the irrigated alfalfa belt of the Bighorn Basin and the Powder River country. Cx. tarsalis is the dominant vector statewide, off pasture, alfalfa, and stock-tank habitat. Yellowstone and Grand Teton National Parks sit too cold and too high for meaningful arboviral transmission, though their summer Aedes hatches off snowmelt punish hikers. Aedes aegypti and Aedes albopictus are not established. EEE is rare. Cool nights compress the season and most of the state stays sparse outside the irrigated valleys. Biting season runs June through August.
Snapshot of the current mosquito situation in Wyoming, drawn from CDC ArboNET surveillance and the regional risk model.
- Risk Level
- Low
- Peak Activity
- July through September
- Dominant Vector
- Western Encephalitis Mosquito (Culex tarsalis) statewide and dominant WNV vector
Where Mosquitoes Breed in Wyoming
Wyoming mosquito habitat is built on the North Platte corridor, the irrigated basins, and the snowmelt-fed mountain valleys. The North Platte River through Casper and on into Nebraska holds the most consequential Cx. tarsalis habitat in the state, with irrigated alfalfa pasture along the river bottoms sustaining summer populations. The Bighorn Basin around Worland and Cody, the Powder River Basin in the northeast, and the Bear River valley in the southwest carry the same agricultural Culex pattern at lower density. The Wind River Range and the Snake River headwaters above Jackson hold sharp snowmelt Aedes hatches at lower elevations. Yellowstone meadows and the Tetons stay cold enough that mosquito pressure collapses above 7000 feet. Cheyenne and Laramie urban storm drains carry the modest Cx. pipiens load.
Hotspot Counties & Areas
- Natrona County (Casper, North Platte River)
- Laramie County (Cheyenne)
- Albany County (Laramie)
- Campbell County (Gillette, Powder River Basin)
- Bighorn Basin (Park, Big Horn, and Washakie counties)
- Goshen and Platte counties (irrigated North Platte)
- Grand Teton National Park (peripheral, snowmelt Aedes)
- Bear River valley (Uinta County)
Seasonal Activity Pattern
Biting starts in mid June across the North Platte corridor and the irrigated basins, peaks through July, and tapers through August. WNV cases concentrate in August across Natrona, Goshen, and the eastern irrigated counties. Cx. tarsalis populations build with the summer irrigation cycle and stay elevated through August. Snowmelt off the Wind River Range, the Bighorns, and the Tetons produces sharp floodwater Aedes pulses on the canyon trails through late June and early July. Cool nights statewide hold daytime activity down and the first hard frost in September ends the season fast.
Monthly Biting Intensity (Mountain West)
Wyoming Mosquito Risk Profile
- WNV burden level
- Low
- about 5 to 20 confirmed cases annually; low absolute count, high per-capita
- EEE risk
- Rare
- Peak biting season
- June through August
- Top urban risk areas
- Cheyenne (Laramie)
- Casper (Natrona)
- Laramie (Albany)
Signature habitat: irrigated alfalfa fields, North Platte River corridor, Bighorn Basin, Yellowstone meadows.
Climate driver: Borderline tier placement; high per-capita WNV but tiny population means single-digit total cases most years.
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Common Mosquitoes in Wyoming
Understanding which mosquitoes are active in Wyoming 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.
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 Wyoming
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 Wyoming?
Mosquito activity winds down after the first hard freeze, which in Wyoming typically arrives around Sep 20. See the local first-frost window and city-by-city freeze dates.
Wyoming first frost datesAlso worried about ticks in Wyoming?
Lyme disease risk and tick activity track different seasonal patterns than mosquitoes. See your Wyoming tick forecast.
View Wyoming tick forecastStay Safe in Wyoming
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