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Las Vegas Mosquito Forecast

Today's mosquito activity in Las Vegas, the week ahead, and what to do about it. Updated hourly.

Bite Index · Sunday, November 8

Low

Mosquito activity in Las Vegas is low today.

Few mosquitoes. You may see one or two at dusk near water.

Worse than a typical November in Clark County (usually around 2).

  • At a two-week average of 63°F, larvae develop slowly and the population stays small whatever the rain.
  • Tonight: a cool 60°F evening, light wind, dry air — poor flying weather, so fewer bites than the population alone would suggest.
  • It's the edge of the season; warm weeks like this one keep it going past the calendar.

The week ahead

Each day's Bite Index, from this week's weather and the rain that is still hatching. Forecast days get less certain as the week goes on.

  1. Today
    18Low75°/46°dry
  2. Mon
    19Low76°/49°dry
  3. Tue
    20Low75°/50°dry
  4. Wed
    20Low75°/65°dry
  5. Thu
    20Low73°/64°dry
  6. Fri
    20Low73°/65°dry
  7. Sat
    18Low70°/65°dry

Protect tonight

You can probably skip repellent tonight.

  1. If you're near a creek, pond or heavy shade at dusk, a light application on ankles and arms is plenty.
  2. Good night to tip out any containers holding water; what you empty now won't hatch next week.
Which repellent, and how much: DEET vs picaridinBest natural repellents

Why Las Vegas's mosquitoes do what they do

Las Vegas is Mojave Desert, and its mosquitoes live on the water people bring: golf courses, parks, washes fed by irrigation runoff, the Las Vegas Wash wetlands, and green pools. The Southern Nevada Health District traps across the valley and announces West Nile-positive samples by ZIP code; 2026's first came in June.

  • Las Vegas Wash and Clark County Wetlands Park: the valley's drainage creates permanent habitat downstream of the city.
  • Irrigation and green pools: golf courses, parks and neglected pools are the urban breeding sites.
  • Aedes aegypti: detected in the valley since 2017 and spreading.
  • Extreme heat and dryness: 110°F afternoons and single-digit humidity ground mosquitoes; dusk and dawn are the only biting windows, and the index weights that.

A typical year in Clark County

What the Bite Index typically reads here each month, from Clark County's 30-year climate normals run through the same model as today's number. The month you're in is marked; the season map shows the same long-run picture for every county.

  1. JJanuary: 0
  2. FFebruary: 0
  3. MMarch: 0
  4. AApril: 5
  5. MMay: 18
  6. JJune: 29
  7. JJuly: 29
  8. AAugust: 38
  9. SSeptember: 35
  10. OOctober: 18
  11. NNovember: 2
  12. DDecember: 0

Local surveillance and West Nile virus

The Bite Index measures nuisance biting, not disease. Clark County's health department traps and tests mosquitoes through the season and publishes positive West Nile pools by ZIP code. When your ZIP has an active advisory, follow it regardless of today's number.

How the Bite Index is scored

The index is a model of conditions, not a mosquito count. Warmth and water set the size of the population, tonight's weather sets how much of it flies, and the season and local reports adjust the result. Every factor and today's value for it is listed here so you can check the number yourself. Warmth and Water are exactly the climate core of our county-level mosquito season map; the map shows that core on 30-year normals for every county, and “typical for this month” is the same model run on this county's normals, so the comparison is like for like.

WWater

Rain over the egg-to-adult window (1.3 in. between Oct 19 and Oct 29), expressed as a monthly rate on the same wetness curve the season map uses. At summer temperatures eggs become biting adults in about a week, so today's mosquitoes are last week's rain. Cool weather stretches the window; hot dry days shrink it. Irrigation, creeks and pools keep a 35% floor even in a drought.

Role scales
Today 100%

TWarmth

The trailing two-week average temperature on the season map's curve: nothing below 50°F, full speed at 78–88°F, a small penalty in extreme heat. Multiplied with Water, so a cool fortnight caps the index however wet it has been.

Role gates
Today 46%

ATonight

Whether the population that exists will actually fly and bite this evening: dusk temperature (65–85°F is ideal), wind (they stop flying around 10 mph), humidity, and rain around sunset. Scales the index between half and full.

Role 0.5–1×
Today 32%

GGround truth

A nudge from local trap counts and reports when we have them. For Las Vegas this is neutral today; the health department's surveillance is linked above and will feed this factor as we wire it in.

Role ±15%
Today neutral

SSeason gate

A multiplier from the calendar: fully open in the city's season months, half-open in the shoulder months, nearly closed in deep winter unless the week is warm. Below a 50°F weekly average the index is simply 0.

Role ×
Today 60%

index = 100 × S × [T × (0.35 + 0.65·W)] × (0.5 + 0.5·A) × (1 + 0.15·G)

Bands: Low 0–20 · Moderate 21–40 · High 41–60 · Very High 61–80 · Severe 81–100. Weather is from Open-Meteo (observations and the 7-day forecast), refreshed hourly. The lag and temperature thresholds follow published work on Culex and Aedes development (Rueda et al. 1990; Cornell NRCC degree-day emergence; JAMCA 2024 on rainfall two to four weeks before trap peaks).

Questions people ask about mosquitoes in Las Vegas

When is mosquito season in Las Vegas?
May through October, peaking from June through September. The health district starts surveillance in April; the first cool nights of November end it.
Why does Las Vegas have mosquitoes at all?
Irrigation and the Las Vegas Wash. Golf courses, parks, green pools and the wetlands downstream of the city hold water in a desert that has none, and Culex breed in it all summer. Heat keeps them hidden until dusk.
Is West Nile virus a risk in Las Vegas?
Yes. Clark County records positive samples most summers and human cases in many years; 2024 was among its worst. The health district's ZIP-code announcements are authoritative; follow them over the index.
Where does this forecast's data come from?
Open-Meteo weather for central Las Vegas, scored by our documented model with desert humidity and heat terms, and compared with Clark County's climate normals run through the same model. Irrigation isn't in the weather data.

Also covers Henderson, North Las Vegas, Summerlin, Spring Valley, Boulder City, Paradise, the Strip, Clark County Wetlands Park: the forecast point is central Las Vegas, and conditions within about 30 miles track it closely. Weather fetched Nov 8, 2:28 PM local time.

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