Mosquito season in Cuyahoga County, OH: when it starts and ends

Mosquito months in Cuyahoga County

In a normal year mosquito season in Cuyahoga County, OH starts around April 17 and ends around October 31, about 28 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 Cuyahoga County, and when

• Start tipping out standing water weekly by April 3.
• Book any yard treatment for mid April, ahead of the July peak.
• Repellent can go away after October 31.
• 35 West Nile cases since 2016: you should wear EPA-registered repellent at dusk June to August, and check OH spray notices.

Cuyahoga County against the rest of OH

Cuyahoga County has the 26th longest season of 88 OH counties, at 197 days against 209 in Gallia County and 177 in Ashtabula County. Its mean temperature is 52.3°F.

• Fayette County: April 11 to October 25 (197 days, 0 WNV)
• Crawford County: April 13 to October 26 (197 days, 0 WNV)
• Lake County: April 18 to November 1 (197 days, 5 WNV)
• Meigs County: April 13 to October 26 (196 days, 1 WNV)

West Nile in Cuyahoga County

From 1999 to 2025, CDC ArboNET counted 381 human West Nile cases in Cuyahoga County (275 neuroinvasive) across 21 years. The worst was 2002 with 220; the latest was 2025.

See how the dates are worked out, and reading the West Nile counts.