Mosquito season in Sullivan County, IN: when it starts and ends
Mosquito months in Sullivan County
In a normal year mosquito season in Sullivan County, IN starts around April 1 and ends around November 1, about 31 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Sullivan 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 1.
- 2 West Nile cases since 2016 (last 2022): you should use repellent at dusk June to August, more so if over 60.
Sullivan County against the rest of IN
Sullivan County has the 13th longest season of 92 IN counties, at 214 days against 231 in Floyd County and 177 in Steuben County. Its mean temperature is 54.6°F.
- Greene County: March 31 to November 3 (217 days, 1 WNV)
- Knox County: April 1 to November 3 (216 days, 0 WNV)
- Martin County: April 2 to November 2 (214 days, 0 WNV)
- Gibson County: April 2 to November 1 (213 days, 0 WNV)
West Nile in Sullivan County
From 1999 to 2025, CDC ArboNET counted 2 human West Nile cases in Sullivan County (2 neuroinvasive) across 2 years. The worst was 2022 with 1; the latest was 2022.
More: how the dates are worked out · when the season starts across the US.