Mosquito season in Madison County, IN: when it starts and ends
Mosquito months in Madison County
In a normal year mosquito season in Madison County, IN starts around April 9 and ends around October 27, about 29 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Madison County, and when
- Start tipping out standing water weekly by March 26.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after October 27.
- 2 West Nile cases since 2016 (last 2025): you should use repellent at dusk June to August, more so if over 60.
Madison County against the rest of IN
Madison County has the 39th longest season of 92 IN counties, at 201 days against 231 in Floyd County and 177 in Steuben County. Its mean temperature is 52.4°F.
- Marion County: April 8 to October 27 (202 days, 18 WNV)
- Hendricks County: April 9 to October 27 (201 days, 1 WNV)
- Boone County: April 10 to October 26 (199 days, 1 WNV)
- Union County: April 10 to October 26 (199 days, 0 WNV)
West Nile in Madison County
From 1999 to 2025, CDC ArboNET counted 12 human West Nile cases in Madison County (6 neuroinvasive) across 7 years. The worst was 2002 with 6; the latest was 2025.
Background: when mosquitoes go away for the winter; how the dates are worked out.