Mosquito season in Clark County, IN: when it starts and ends
Mosquito months in Clark County
In a normal year mosquito season in Clark County, IN starts around March 26 and ends around November 6, about 32 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Clark County, and when
- Start tipping out standing water weekly by March 12.
- Book any yard treatment for late March, ahead of the July peak.
- Repellent can go away after November 6.
- 4 West Nile cases since 2016 (last 2025): you should use repellent at dusk June to August, more so if over 60.
Clark County against the rest of IN
Clark County has the 4th longest season of 92 IN counties, at 224 days against 231 in Floyd County and 177 in Steuben County. Its mean temperature is 56.9°F.
- Vanderburgh County: March 25 to November 8 (228 days, 17 WNV)
- Spencer County: March 26 to November 6 (225 days, 0 WNV)
- Posey County: March 30 to November 5 (220 days, 0 WNV)
- Daviess County: March 30 to November 4 (219 days, 0 WNV)
West Nile in Clark County
From 1999 to 2025, CDC ArboNET counted 7 human West Nile cases in Clark County (6 neuroinvasive) across 6 years. The worst was 2017 with 2; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.