Today's Mosquito Risk in Nevada: 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 30 confirmed cases annually
- Based on CDC ArboNET surveillance data
- Risk Tier
- Tier 2: High Pressure
- Las Vegas Aedes aegypti invasion adds a daytime biter to a state otherwise dominated by irrigated-farmland Cx. tarsalis.
- Per mosquito-risk-model regional tier
- Highest-Risk Areas
- Clark, Washoe (WNV and urban Aedes aegypti); Douglas (Carson Valley Cx. tarsalis)
Current Situation in Nevada
Nevada runs a low to moderate WNV burden of roughly 10 to 30 confirmed human cases annually, with risk concentrated in the Las Vegas Valley and the Truckee and Carson Valley irrigated corridors. The defining shift of the past decade is the Aedes aegypti invasion of Las Vegas, first detected in Clark County in 2017 and now established across the metro, adding a daytime urban biter to a state otherwise dominated by irrigated-farmland Cx. tarsalis. Aedes albopictus presence is limited. EEE is rare. Outside the Las Vegas metro, the Reno and Sparks area along the Truckee River and the Carson Valley irrigated alfalfa belt sustain seasonal Cx. tarsalis populations off the Sierra snowmelt cycle. The Great Basin high desert, the Ruby Mountains, and the eastern range basins stay largely mosquito-free except where livestock water and irrigation concentrate. Biting season runs May through September.
Snapshot of the current mosquito situation in Nevada, drawn from CDC ArboNET surveillance and the regional risk model.
- Risk Level
- Low
- Peak Activity
- April through October
- Dominant Vector
- Western Encephalitis Mosquito (Culex tarsalis) statewide and dominant WNV vector
Where Mosquitoes Breed in Nevada
Nevada mosquito habitat is concentrated in three corridors. The Las Vegas Valley urban core in Clark County holds established Aedes aegypti through storm drains, ornamental water features, and backyard containers, with population centers in Las Vegas, Henderson, and North Las Vegas. The Lake Mead shoreline and the Colorado River below Hoover Dam carry seasonal Cx. tarsalis pulses. The Truckee River through Reno and Sparks and the Carson River through Carson City and Minden hold irrigated alfalfa and pasture habitat that sustains Cx. tarsalis through summer off the Sierra snowmelt cycle. Pyramid Lake on the Paiute reservation north of Reno carries seasonal shoreline marsh hatches. The Humboldt River across northern Nevada and the Walker Lake basin produce isolated wetland habitat. The Great Basin high desert, the Ruby Mountains, and most of the central range basins stay too dry for sustained mosquito populations. The Lake Tahoe shoreline runs cool and mostly mosquito-free.
Hotspot Counties & Areas
- Clark County (Las Vegas, Henderson, North Las Vegas)
- Washoe County (Reno, Sparks, Truckee River)
- Lake Mead shoreline (Colorado River)
- Carson Valley (Douglas County)
- Pyramid Lake (Washoe County)
- Humboldt River corridor (northern Nevada)
- Walker Lake basin
- Lake Tahoe shoreline (Douglas and Washoe counties)
Seasonal Activity Pattern
Biting starts in early May in the Las Vegas Valley and along the Truckee and Carson corridors, peaks July through August, and tapers through September. WNV cases concentrate in August across Clark and Washoe counties. Cx. tarsalis populations build through July with the Sierra snowmelt and irrigation cycle in the Truckee and Carson Valleys. Las Vegas Aedes aegypti daytime biting runs from May through October, with peak intensity in August when summer monsoon edge moisture pushes into southern Nevada. The high desert stays dry and mostly biter-free outside isolated water features and stock tanks.
Monthly Biting Intensity (Southwest)
Nevada Mosquito Risk Profile
- WNV burden level
- Low
- about 10 to 30 confirmed cases annually
- EEE risk
- Rare
- Peak biting season
- May through September
- Top urban risk areas
- Las Vegas (Clark)
- Henderson (Clark)
- Reno (Washoe)
- North Las Vegas (Clark)
Signature habitat: Las Vegas urban storm drains, Truckee Valley irrigated farmland, Humboldt River wetlands.
Climate driver: Las Vegas Aedes aegypti invasion adds a daytime biter to a state otherwise dominated by irrigated-farmland Cx. tarsalis.
Check Your Local Mosquito Risk
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Common Mosquitoes in Nevada
Understanding which mosquitoes are active in Nevada helps you identify threats and take appropriate precautions. Click any card for details.
Southern House Mosquito
Culex quinquefasciatus
Risk: West Nile virus, St. Louis encephalitis, dog heartworm.
Key feature: Medium brown body with banded abdominal segments and no leg stripes.
Active: Year-round in the deep South; summer peak elsewhere. Most active from dusk through the first few hours after sunset.
Yellow Fever Mosquito
Aedes aegypti
Risk: Zika, dengue, yellow fever, chikungunya.
Key feature: Black body with white lyre-shaped markings on the thorax.
Active: Year-round in southern Florida and the Gulf; summer-only further north.
West Nile Virus
Vector: Southern House Mosquito
West Nile Virus
The most common mosquito-borne illness in the US. About 80% of infections cause no symptoms; less than 1% develop neuroinvasive disease.
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 Nevada
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 Nevada?
Live water temperatures and swim conditions for Lake Mead.
See Nevada lake temperaturesWhen does mosquito season end in Nevada?
Mosquito activity winds down after the first hard freeze, which in Nevada typically arrives around Oct 2. See the local first-frost window and city-by-city freeze dates.
Nevada first frost datesAlso worried about ticks in Nevada?
Lyme disease risk and tick activity track different seasonal patterns than mosquitoes. See your Nevada tick forecast.
View Nevada tick forecastStay Safe in Nevada
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