Mosquito season in Porter County, IN: when it starts and ends
Mosquito months in Porter County
In a normal year mosquito season in Porter County, IN starts around April 15 and ends around October 24, about 27 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Porter County, and when
- Start tipping out standing water weekly by April 1.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 24.
- 10 West Nile cases since 2016: you should wear EPA-registered repellent at dusk July to August, and check IN spray notices.
Porter County against the rest of IN
Porter County has the 60th longest season of 92 IN counties, at 192 days against 231 in Floyd County and 177 in Steuben County. Its mean temperature is 50.6°F.
- Cass County: April 14 to October 24 (192 days, 0 WNV)
- Fayette County: April 14 to October 23 (192 days, 0 WNV)
- Ripley County: April 17 to October 26 (192 days, 1 WNV)
- Montgomery County: April 14 to October 23 (191 days, 0 WNV)
West Nile in Porter County
From 1999 to 2025, CDC ArboNET counted 45 human West Nile cases in Porter County (26 neuroinvasive) across 15 years. The worst was 2006 with 12; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.