Mosquito season in Leavenworth County, KS: when it starts and ends

Mosquito months in Leavenworth County

In a normal year mosquito season in Leavenworth County, KS starts around April 9 and ends around October 27, 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 Leavenworth County, and when

• Start tipping out standing water weekly by March 26.
• Book any yard treatment for early April, ahead of the July peak.
• Repellent can go away after October 27.
• 2 West Nile cases since 2016 (last 2025): you should use repellent at dusk June to August, more so if over 60.

Leavenworth County against the rest of KS

Leavenworth County has the 63rd longest season of 105 KS counties, at 201 days against 227 in Cherokee County and 178 in Thomas County. Its mean temperature is 53.8°F.

• Pawnee County: April 12 to October 31 (202 days, 1 WNV)
• Brown County: April 8 to October 26 (201 days, 1 WNV)
• Reno County: April 10 to October 28 (201 days, 11 WNV)
• Riley County: April 10 to October 28 (201 days, 1 WNV)

West Nile in Leavenworth County

From 1999 to 2025, CDC ArboNET counted 4 human West Nile cases in Leavenworth County (1 neuroinvasive) across 4 years. The worst was 2025 with 1; the latest was 2025.

More: how the dates are worked out · when the season starts across the US.