Mosquito season in Harris County, TX: when it starts and ends
Mosquito months in Harris County
In a normal year mosquito season in Harris County, TX starts around January 27 and ends around January 2, about 49 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Harris County, and when
- Start tipping out standing water weekly by January 13.
- Book any yard treatment for late January, ahead of the August peak.
- Repellent can go away after January 2.
- 188 West Nile cases since 2016: you should wear EPA-registered repellent at dusk April to October, and check TX spray notices.
Harris County against the rest of TX
Harris County has the 20th longest season of 254 TX counties, at 340 days against 365 in Cameron County and 191 in Lipscomb County. Its mean temperature is 70.6°F.
- Zavala County: January 20 to December 26 (340 days, 2 WNV)
- Chambers County: January 25 to December 31 (340 days, 2 WNV)
- Trinity County: February 6 to January 12 (340 days, 2 WNV)
- Jefferson County: January 28 to January 1 (338 days, 8 WNV)
West Nile in Harris County
From 1999 to 2025, CDC ArboNET counted 824 human West Nile cases in Harris County (659 neuroinvasive) across 24 years. The worst was 2014 with 134; the latest was 2025.
More: how the dates are worked out · where mosquitoes never stop.