Mosquito season in Knox County, IN: when it starts and ends
Mosquito months in Knox County
In a normal year mosquito season in Knox County, IN starts around April 1 and ends around November 3, about 31 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Knox County, and when
- Start tipping out standing water weekly by March 18.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after November 3.
- No West Nile cases since 2016, so bites in Knox County are a nuisance; check window screens.
Knox County against the rest of IN
Knox County has the 12th longest season of 92 IN counties, at 216 days against 231 in Floyd County and 177 in Steuben County. Its mean temperature is 55.7°F.
- Perry County: March 31 to November 4 (218 days, 1 WNV)
- Greene County: March 31 to November 3 (217 days, 1 WNV)
- Sullivan County: April 1 to November 1 (214 days, 2 WNV)
- Martin County: April 2 to November 2 (214 days, 0 WNV)
West Nile in Knox County
From 1999 to 2025, CDC ArboNET counted 6 human West Nile cases in Knox County (1 neuroinvasive) across 4 years. The worst was 2003 with 2; the latest was 2012.
Background: when the season starts across the US; how the dates are worked out.