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Knoxville Mosquito Forecast

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

Bite Index · Sunday, November 8

Low

Mosquito activity in Knoxville is low today.

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

About normal for November in Knox County (typically around 0).

  • Off-season: even with rain and warmth, populations are a fraction of summer's.
  • Only 0.2 in. of rain Oct 15–Oct 28, so few new breeding sites; what's biting is coming from irrigation, pools and creeks.
  • Tonight: a cool 51°F evening, light wind — poor flying weather, so fewer bites than the population alone would suggest.

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
    1Low66°/36°dry
  2. Mon
    1Low67°/40°dry
  3. Tue
    1Low64°/41°dry
  4. Wed
    1Low69°/44°dry
  5. Thu
    1Low58°/42°0.3 in
  6. Fri
    1Low43°/37°0.2 in
  7. Sat
    0Low47°/32°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 Knoxville's mosquitoes do what they do

Knoxville sits in the Tennessee Valley where the Holston and French Broad form the Tennessee River, with humid summers and ridges that trap the air. The Knox County Health Department traps across the county, announces West Nile detections by area and schedules spraying in response, most summers in several neighborhoods.

  • River valley: the Tennessee and its tributaries, plus Fort Loudoun Lake's coves, hold water and humidity.
  • Humid summers: July and August dusk conditions are ideal for flight.
  • Tree canopy: the Asian tiger mosquito dominates shaded yards by day.
  • Real winter: frosts from late October end the season.

A typical year in Knox County

What the Bite Index typically reads here each month, from Knox 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: 9
  5. MMay: 43
  6. JJune: 68
  7. JJuly: 81
  8. AAugust: 81
  9. SSeptember: 68
  10. OOctober: 20
  11. NNovember: 0
  12. DDecember: 0

Local surveillance and West Nile virus

The Bite Index measures nuisance biting, not disease. Knox 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 (0.2 in. between Oct 15 and Oct 28), 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 0%

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 30%

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 8%

GGround truth

A nudge from local trap counts and reports when we have them. For Knoxville 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 15%

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 Knoxville

When is mosquito season in Knoxville?
May through September, peaking in July and August. The first frost, usually late October, ends it.
Why does Knox County spray certain neighborhoods?
When trapped mosquitoes in an area test positive for West Nile, the Health Department treats that area and announces it. Those notices name the neighborhoods and the nights.
Is West Nile virus a risk in Knoxville?
Yes. Knox County detects it in mosquitoes most summers and has recorded human cases. The Health Department's releases are authoritative; follow them over the index.
Where does this forecast's data come from?
Open-Meteo weather for downtown Knoxville, scored by our documented model and compared with Knox County's climate normals. Not a trap count.

Also covers Farragut, Oak Ridge, Maryville, Powell, Halls, Seymour, Ijams Nature Center, the Urban Wilderness: the forecast point is central Knoxville, and conditions within about 30 miles track it closely. Weather fetched Nov 8, 5:28 PM local time.

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