Mosquito season in Johnson County, IN: when it starts and ends
Mosquito months in Johnson County
In a normal year mosquito season in Johnson County, IN starts around April 12 and ends around October 24, about 28 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Johnson County, and when
- Start tipping out standing water weekly by March 29.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 24.
- 2 West Nile cases since 2016 (last 2024): you should use repellent at dusk June to August, more so if over 60.
Johnson County against the rest of IN
Johnson County has the 49th longest season of 92 IN counties, at 196 days against 231 in Floyd County and 177 in Steuben County. Its mean temperature is 51.7°F.
- Blackford County: April 12 to October 26 (196 days, 0 WNV)
- Fountain County: April 12 to October 25 (196 days, 0 WNV)
- Morgan County: April 12 to October 25 (196 days, 2 WNV)
- Wayne County: April 12 to October 24 (195 days, 1 WNV)
West Nile in Johnson County
From 1999 to 2025, CDC ArboNET counted 4 human West Nile cases in Johnson County (2 neuroinvasive) across 4 years. The worst was 2024 with 1; the latest was 2024.
More: how the dates are worked out · when mosquitoes go away for the winter.