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Sarasota Mosquito Forecast

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

Bite Index · Sunday, November 8

Severe

Severe mosquito activity in Sarasota today and easing through the week. Expect to be bitten within minutes outdoors at dusk.

Swarming conditions. Expect bites within a minute or two outside at dusk.

Worse than a typical November in Sarasota County (usually around 61).

  • 2.0 in. of rain Oct 24–Oct 31 has had time to hatch: this is the surge from that storm.
  • Tonight: a 68°F evening, light wind — good flying weather for mosquitoes.
  • A two-week average of 75°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
    89Severe78°/62°dry
  2. Mon
    88Severe75°/62°dry
  3. Tue
    88Severe83°/65°dry
  4. Wed
    88Severe82°/72°dry
  5. Thu
    85Severe80°/72°dry
  6. Fri
    66V·High73°/63°0.2 in
  7. Sat
    63V·High64°/56°dry

Protect tonight

Treat the outdoors like a swarm: cover up and use a full-strength repellent.

  1. 25–30% DEET or 20% picaridin on every bit of exposed skin, plus permethrin-treated clothing for anything longer than a quick trip outside.
  2. Keep kids and pets in around dusk and dawn; schedule outdoor time for midday when it's hottest and driest.
  3. If your health department has an active West Nile advisory for your ZIP, follow it over anything on this page.
Which repellent, and how much: DEET vs picaridinBest natural repellents

Why Sarasota's mosquitoes do what they do

Sarasota's barrier islands, bays and inland sloughs give it both salt-marsh and freshwater mosquitoes, and its Mosquito Management Services runs a trap network and sentinel chickens year-round. In 2023 the county recorded the first locally acquired malaria in the United States in two decades, a reminder of what Anopheles in the sloughs can do.

  • Barrier islands and bays: Sarasota Bay, Lemon Bay and the Myakka marshes produce salt-marsh broods on spring tides.
  • Sloughs and wetlands: freshwater habitat for Anopheles and Culex inland.
  • Wet season: near-daily storms from June through September.
  • Sentinel chickens: the county's flocks detect West Nile and EEE before people get sick.

A typical year in Sarasota County

What the Bite Index typically reads here each month, from Sarasota 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: 5
  2. FFebruary: 6
  3. MMarch: 30
  4. AApril: 62
  5. MMay: 76
  6. JJune: 86
  7. JJuly: 86
  8. AAugust: 86
  9. SSeptember: 86
  10. OOctober: 81
  11. NNovember: 61
  12. DDecember: 22

Local surveillance and West Nile virus

The Bite Index measures nuisance biting, not disease. Sarasota 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 (2.0 in. between Oct 24 and Oct 31), 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 89%

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 100%

GGround truth

A nudge from local trap counts and reports when we have them. For Sarasota 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 100%

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 Sarasota

When is mosquito season in Sarasota?
Year-round, peaking from June through October. The driest winter weeks are the lull; salt-marsh broods can appear any month the marsh floods.
Why was there malaria in Sarasota?
Anopheles mosquitoes that can carry malaria breed in the county's freshwater sloughs. In 2023 they picked up the parasite from an infected traveler and passed it on locally; the county's aggressive treatment ended the cluster.
Is West Nile virus a risk in Sarasota?
Yes. The county's sentinel chickens and traps detect West Nile and EEE most years, and the health department issues advisories. Follow those over the index.
Where does this forecast's data come from?
Open-Meteo weather for downtown Sarasota, scored by our documented model and compared with Sarasota County's season-map climatology. It does not include tide data.

Also covers Bradenton, Venice, North Port, Siesta Key, Lakewood Ranch, Longboat Key, Myakka River State Park, Lido Key: the forecast point is central Sarasota, and conditions within about 30 miles track it closely. Weather fetched Nov 8, 5:28 PM local time.

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