Mosquito season in Spencer County, IN: when it starts and ends
Mosquito months in Spencer County
In a normal year mosquito season in Spencer County, IN starts around March 26 and ends around November 6, about 32 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Spencer County, and when
- Start tipping out standing water weekly by March 12.
- Book any yard treatment for late March, ahead of the July peak.
- Repellent can go away after November 6.
- No West Nile cases since 2016, so bites in Spencer County are a nuisance; check window screens.
Spencer County against the rest of IN
Spencer County has the 3rd longest season of 92 IN counties, at 225 days against 231 in Floyd County and 177 in Steuben County. Its mean temperature is 56.6°F.
- Floyd County: March 23 to November 9 (231 days, 2 WNV)
- Vanderburgh County: March 25 to November 8 (228 days, 17 WNV)
- Clark County: March 26 to November 6 (224 days, 4 WNV)
- Posey County: March 30 to November 5 (220 days, 0 WNV)
West Nile in Spencer County
From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Spencer County (1 neuroinvasive) across 1 year. The worst was 2012 with 1; the latest was 2012.
Background: when the season starts across the US; how the dates are worked out.