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

Mosquito months in Henderson County

In a normal year mosquito season in Henderson County, KY starts around March 31 and ends around November 4, about 31 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 Henderson County, and when

• Start tipping out standing water weekly by March 17.
• Book any yard treatment for late March, ahead of the July peak.
• Repellent can go away after November 4.
• 3 West Nile cases since 2016 (last 2025): you should use repellent at dusk June to August, more so if over 60.

Henderson County against the rest of KY

Henderson County has the 33rd longest season of 120 KY counties, at 218 days against 249 in Lyon County and 180 in Shelby County. Its mean temperature is 56.6°F.

• Washington County: March 31 to November 5 (219 days, 0 WNV)
• Fayette County: March 31 to November 4 (218 days, 10 WNV)
• Trimble County: March 31 to November 4 (218 days, 0 WNV)
• Wolfe County: March 31 to November 4 (218 days, 0 WNV)

West Nile in Henderson County

From 1999 to 2025, CDC ArboNET counted 4 human West Nile cases in Henderson County (3 neuroinvasive) across 2 years. The worst was 2025 with 3; the latest was 2025.

Background: when mosquitoes go away for the winter; how the dates are worked out.