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Fort Worth Mosquito Forecast

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

Bite Index · Sunday, November 8

High

High mosquito activity in Fort Worth today. Cover up or use repellent after 6 pm.

Bites within a few minutes outdoors at dusk. Repellent or long sleeves pay off.

About normal for November in Tarrant County.

  • Only 0.2 in. of rain Oct 19–Oct 30, so few new breeding sites; what's biting is coming from irrigation, pools and creeks.
  • Tonight: a cool 63°F evening, light wind — good flying weather for mosquitoes.
  • A two-week average of 68°F keeps populations growing, just more slowly than midsummer.

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
    50High71°/57°dry
  2. Mon
    53High73°/54°dry
  3. Tue
    54High75°/61°0.1 in
  4. Wed
    49High80°/61°dry
  5. Thu
    48High68°/53°dry
  6. Fri
    39Mod.59°/47°dry
  7. Sat
    53High72°/49°dry

Protect tonight

Use repellent for any time outside after about 6 pm.

  1. 20% picaridin or 20–30% DEET for the evening; follow the label's reapplication window.
  2. Long sleeves and pants in light colors cut bites roughly in half on their own.
  3. Skip the yard work at dusk: the hour around sunset is the heaviest biting of the day.
Which repellent, and how much: DEET vs picaridinBest natural repellents

Why Fort Worth's mosquitoes do what they do

Fort Worth shares Dallas's clay soil and hot summers but sits on the Trinity's West and Clear Forks, with more open prairie at its edges. Tarrant County Public Health traps across the county from spring through fall and publishes weekly arbovirus reports; its West Nile season officially opened in mid-May in 2026.

  • Trinity forks and the Fort Worth Nature Center: river-bottom habitat that floods and drains slowly.
  • Clay soil: spring rain stands in yards and bar ditches for a week or more.
  • Urban Culex: storm drains and neglected pools carry the West Nile vector through dry Augusts.
  • Hard freezes: the season ends abruptly with the first freeze, usually late November.

A typical year in Tarrant County

The long-run mosquito index by month from our season map (NOAA climate normals plus effort-corrected sightings). Today's Bite Index is the live version of this; the month you're in is marked.

  1. JJanuary: 0
  2. FFebruary: 0
  3. MMarch: 30
  4. AApril: 55
  5. MMay: 83
  6. JJune: 100
  7. JJuly: 95
  8. AAugust: 83
  9. SSeptember: 92
  10. OOctober: 75
  11. NNovember: 51
  12. DDecember: 0

Local surveillance and West Nile virus

The Bite Index measures nuisance biting, not disease. Tarrant 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. Four weather factors are combined on a 0–100 scale, then scaled by the season. Every factor and today's value for it is listed here so you can check the number yourself. It uses the same temperature curve and rain logic as our county-level mosquito season map, which has been validated against effort-corrected sighting data across 41 states.

BBreeding pressure

Rain 7–14 days ago (0.2 in. between Oct 19 and Oct 30). Eggs need water to hatch, and at summer temperatures the egg-to-biting-adult cycle takes about a week, so today's mosquitoes are last week's rain. Cool weather stretches the window; hot dry days shrink it as shallow water evaporates.

Weight 40%
Today 0%

DDevelopment

The trailing two-week average temperature, on the same curve as our national season map: nothing below 50°F, full speed at 78–88°F, a small penalty in extreme heat.

Weight 25%
Today 63%

ATonight's activity

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.

Weight 25%
Today 84%

GGround truth

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

Weight 10%
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.

Weight ×
Today 100%

index = 100 × S × (0.40 × (0.2 + 0.8·B) + 0.25 × D + 0.25 × A + 0.10 × (0.5 + 0.5·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 Fort Worth

When is mosquito season in Fort Worth?
April through October, peaking with spring rains in May and June and again with West Nile-carrying Culex in late summer. Tarrant County's surveillance season runs roughly May to November.
Why are mosquitoes worse a week after it rains?
Rain fills the clay-bottomed low spots and ditches; at North Texas summer temperatures eggs become biting adults in 7 to 10 days. The index looks back at exactly that window.
Is West Nile virus a risk in Fort Worth?
Yes. Tarrant County reports positive pools most summers and publishes them weekly by city. When your city is listed, follow the county's guidance over anything on this page.
Where does this forecast's data come from?
Open-Meteo weather for central Fort Worth, scored by our documented model and compared with Tarrant County's season-map climatology. A model, not a trap count.

Also covers Arlington, Keller, Southlake, Grapevine, Mansfield, Burleson, the Stockyards, Trinity Trails: the forecast point is central Fort Worth, and conditions within about 30 miles track it closely. Weather fetched Nov 8, 12:38 PM local time.

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