Mosquito season in Grimes County, TX: when it starts and ends

Mosquito months in Grimes County

In a normal year mosquito season in Grimes County, TX starts around February 19 and ends around December 3, about 41 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 Grimes County, and when

• Start tipping out standing water weekly by February 5.
• Book any yard treatment for mid February, ahead of the August peak.
• Repellent can go away after December 3.
• 6 West Nile cases since 2016 (last 2025): you should use repellent at dusk May to October, more so if over 60.

Grimes County against the rest of TX

Grimes County has the 73rd longest season of 254 TX counties, at 287 days against 365 in Cameron County and 191 in Lipscomb County. Its mean temperature is 68.6°F.

• Navarro County: February 22 to December 7 (288 days, 10 WNV)
• El Paso County: February 16 to November 30 (287 days, 89 WNV)
• Cherokee County: February 23 to December 7 (287 days, 3 WNV)
• Wilson County: February 21 to December 3 (285 days, 1 WNV)

West Nile in Grimes County

From 1999 to 2025, CDC ArboNET counted 12 human West Nile cases in Grimes County (8 neuroinvasive) across 6 years. The worst was 2024 with 3; the latest was 2025.

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