Mosquito forecast
El Paso Mosquito Forecast
Today's mosquito activity in El Paso, the week ahead, and what to do about it. Updated hourly.Today's mosquito activity in El Paso on a 0–100 Bite Index, the week ahead, and what to do about it. Built from the rain and temperature that drive El Paso County's trap counts; updated hourly.
Bite Index · Sunday, November 8
Low
Mosquito activity in El Paso is low today.
Few mosquitoes. You may see one or two at dusk near water.
About normal for November in El Paso County (typically around 0).
- Off-season: even with rain and warmth, populations are a fraction of summer's.
- Tonight: a cool 54°F evening, light wind — poor flying weather, so fewer bites than the population alone would suggest.
- At a two-week average of 63°F, larvae develop slowly and the population stays small whatever the rain.
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.
- Today4LowLow63°/50°dry
- Mon5LowLow66°/48°dry
- Tue5LowLow69°/44°dry
- Wed5LowLow72°/59°dry
- Thu5LowLow70°/60°dry
- Fri4LowLow69°/59°dry
- Sat4LowLow71°/61°dry
Protect tonight
You can probably skip repellent tonight.
- If you're near a creek, pond or heavy shade at dusk, a light application on ankles and arms is plenty.
- Good night to tip out any containers holding water; what you empty now won't hatch next week.
Why El Paso's mosquitoes do what they do
El Paso is Chihuahuan Desert on the Rio Grande, and its mosquitoes live on the river, the irrigation canals of the Upper Valley and the monsoon storms of late summer. The city's Public Health department traps and tests through the season and its Environmental Services crews fog after positive pools; mosquitoes with West Nile and St. Louis encephalitis turn up most summers.
- Rio Grande and canals: the valley's irrigation system is the city's permanent breeding habitat.
- Monsoon: July–September storms add rain and humidity; the surge follows ten days later.
- Culex tarsalis and quinquefasciatus: both West Nile vectors are present.
- Dry heat: outside the monsoon the index stays low.
A typical year in El Paso County
What the Bite Index typically reads here each month, from El Paso 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.
- JJanuary: 0
- FFebruary: 0
- MMarch: 0
- AApril: 2
- MMay: 12
- JJune: 31
- JJuly: 51
- AAugust: 63
- SSeptember: 51
- OOctober: 15
- NNovember: 0
- DDecember: 0
Local surveillance and West Nile virus
The Bite Index measures nuisance biting, not disease. El Paso 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.
- City of El Paso Public Health — West Nile virus
Trap surveillance and testing, vector-control fogging, and the city's climate-ready guidance.
- Texas DSHS — Arbovirus weekly reports
Statewide weekly West Nile and other arbovirus reports.
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 (1.2 in. between Oct 20 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.
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.
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.
GGround truth
A nudge from local trap counts and reports when we have them. For El Paso this is neutral today; the health department's surveillance is linked above and will feed this factor as we wire it in.
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.
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 El Paso
- When is mosquito season in El Paso?
- June through September, peaking with the monsoon in August. The Upper Valley's irrigation keeps some activity going outside that window.
- Why are the Upper Valley and the river so bad?
- Irrigation canals and the river are the only permanent water in the desert, so that is where mosquitoes breed year-round. Monsoon storms then add rain across the whole city.
- Is West Nile virus a risk in El Paso?
- Yes. El Paso County detects West Nile and SLE in mosquito pools most summers and records human cases in many years. The city's announcements are authoritative; follow them over the index.
- Where does this forecast's data come from?
- Open-Meteo weather for downtown El Paso, scored by our documented model with desert humidity and heat terms, and compared with El Paso County's season-map climatology. Irrigation isn't in the weather data.
Also covers Las Cruces, Socorro, Horizon City, Canutillo, Sunland Park, Fort Bliss, the Upper Valley, Ascarate Park: the forecast point is central El Paso, and conditions within about 30 miles track it closely. Weather fetched Nov 8, 3:28 PM local time.