Mosquito season in Marion County, KY: when it starts and ends

Mosquito months in Marion County

In a normal year mosquito season in Marion County, KY starts around April 11 and ends around October 30, about 29 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 Marion County, and when

• Start tipping out standing water weekly by March 28.
• Book any yard treatment for mid April, ahead of the July peak.
• Repellent can go away after October 30.
• No West Nile cases since 2016, so bites in Marion County are a nuisance; check window screens.

Marion County against the rest of KY

Marion County has the 103rd longest season of 120 KY counties, at 202 days against 249 in Lyon County and 180 in Shelby County. Its mean temperature is 55.9°F.

• Casey County: April 11 to October 30 (202 days, 0 WNV)
• Gallatin County: April 11 to October 30 (202 days, 0 WNV)
• Taylor County: April 11 to October 30 (202 days, 0 WNV)
• Bell County: April 10 to October 28 (201 days, 0 WNV)

West Nile in Marion County

From 1999 to 2025, CDC ArboNET counted 2 human West Nile cases in Marion County (2 neuroinvasive) across 2 years. The worst was 2003 with 1; the latest was 2003.

See how the dates are worked out, and when mosquitoes go away for the winter.