Mosquito season in Harrison County, WV: when it starts and ends

Mosquito months in Harrison County

In a normal year mosquito season in Harrison County, WV starts around April 10 and ends around October 28, 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 Harrison County, and when

• Start tipping out standing water weekly by March 27.
• Book any yard treatment for early April, ahead of the July peak.
• Repellent can go away after October 28.
• 1 West Nile case since 2016 (last 2025): you should use repellent at dusk June to August, more so if over 60.

Harrison County against the rest of WV

Harrison County has the 20th longest season of 55 WV counties, at 201 days against 224 in Cabell County and 162 in Randolph County. Its mean temperature is 53.6°F.

• Marion County: April 8 to October 26 (202 days, 0 WNV)
• Fayette County: April 8 to October 26 (201 days, 0 WNV)
• Pleasants County: April 10 to October 28 (201 days, 0 WNV)
• Gilmer County: April 11 to October 29 (201 days, 0 WNV)

West Nile in Harrison County

From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Harrison County (1 neuroinvasive) across 1 year. The worst was 2025 with 1; the latest was 2025.

See how the dates are worked out, and when the season starts across the US.