Mosquito season in Vanderburgh County, IN: when it starts and ends

Mosquito months in Vanderburgh County

In a normal year mosquito season in Vanderburgh County, IN starts around March 25 and ends around November 8, about 33 weeks.

1. Jan
2. Feb
3. Mar
4. Apr
5. May
6. Jun
7. Jul
8. Aug
9. Sep
10. Oct
11. Nov
12. Dec

What to do in Vanderburgh County, and when

• Start tipping out standing water weekly by March 11.
• Book any yard treatment for late March, ahead of the July peak.
• Repellent can go away after November 8.
• 17 West Nile cases since 2016: you should wear EPA-registered repellent at dusk June to September, and check IN spray notices.

Vanderburgh County against the rest of IN

Vanderburgh County has the 2nd longest season of 92 IN counties, at 228 days against 231 in Floyd County and 177 in Steuben County. Its mean temperature is 58°F.

• Floyd County: March 23 to November 9 (231 days, 2 WNV)
• Spencer County: March 26 to November 6 (225 days, 0 WNV)
• Clark County: March 26 to November 6 (224 days, 4 WNV)

West Nile in Vanderburgh County

From 1999 to 2025, CDC ArboNET counted 38 human West Nile cases in Vanderburgh County (26 neuroinvasive) across 13 years. The worst was 2025 with 10; the latest was 2025.

Background: reading the West Nile counts; how the dates are worked out.