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Milwaukee Mosquito Forecast

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

Bite Index · Sunday, November 8

Low

Mosquito activity in Milwaukee is low today.

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

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

  • Off-season: even with rain and warmth, populations are a fraction of summer's.
  • At a two-week average of 52°F, larvae develop slowly and the population stays small whatever the rain.
  • Only 0.4 in. of rain Oct 8–Oct 23, so few new breeding sites; what's biting is coming from irrigation, pools and creeks.

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
    0Low61°/41°dry
  2. Mon
    0Low58°/36°dry
  3. Tue
    0Low59°/40°dry
  4. Wed
    0Low52°/47°0.3 in
  5. Thu
    0Low47°/36°0.2 in
  6. Fri
    0Low40°/35°dry
  7. Sat
    0Low44°/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 Milwaukee's mosquitoes do what they do

Milwaukee sits on Lake Michigan where three rivers meet, with a short, humid summer and the cool lake breeze that keeps the lakefront quieter than the inland neighborhoods. The city's Health Department traps and tests through the season and announced West Nile-positive mosquitoes in July 2026, earlier than most years.

  • River corridors: the Milwaukee, Menomonee and Kinnickinnic Rivers and the Menomonee Valley hold water through the summer.
  • Lake effect: cooler, breezier evenings near the lake; the inland neighborhoods run hotter and buggier.
  • Catch basins: urban Culex pipiens breed in storm drains; a hot dry July concentrates them.
  • Short season: June through September; the index is zero from October to May.

A typical year in Milwaukee County

What the Bite Index typically reads here each month, from Milwaukee 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: 0
  5. MMay: 5
  6. JJune: 42
  7. JJuly: 61
  8. AAugust: 62
  9. SSeptember: 42
  10. OOctober: 5
  11. NNovember: 0
  12. DDecember: 0

Local surveillance and West Nile virus

The Bite Index measures nuisance biting, not disease. Milwaukee 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 (0.4 in. between Oct 8 and Oct 23), 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 8%

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 8%

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 0%

GGround truth

A nudge from local trap counts and reports when we have them. For Milwaukee 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 Milwaukee

When is mosquito season in Milwaukee?
June through September, peaking in July and August. The first frost, usually October, ends it.
Why is the lakefront better than inland?
Lake Michigan keeps the shore several degrees cooler with a steady breeze, and mosquitoes stop flying around 10 mph. Inland neighborhoods and the river valleys run above the citywide index.
Is West Nile virus a risk in Milwaukee?
Yes, in late summer. The Health Department finds positive pools most years and Wisconsin records human cases. Its announcements are authoritative; follow them over the index.
Where does this forecast's data come from?
Open-Meteo weather for downtown Milwaukee, scored by our documented model with the northern breeding lag. Not a trap count.

Also covers Wauwatosa, West Allis, Waukesha, Shorewood, Oak Creek, Brookfield, the Lakefront, Havenwoods: the forecast point is central Milwaukee, and conditions within about 30 miles track it closely. Weather fetched Nov 8, 4:28 PM local time.

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