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

Mosquito months in Liberty County

In a normal year mosquito season in Liberty County, TX starts around January 30 and ends around December 22, about 47 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 Liberty County, and when

• Start tipping out standing water weekly by January 16.
• Book any yard treatment for late January, ahead of the August peak.
• Repellent can go away after December 22.
• 4 West Nile cases since 2016 (last 2025): you should use repellent at dusk May to October, more so if over 60.

Liberty County against the rest of TX

Liberty County has the 35th longest season of 254 TX counties, at 326 days against 365 in Cameron County and 191 in Lipscomb County. Its mean temperature is 68.8°F.

• Webb County: January 31 to December 27 (330 days, 3 WNV)
• Lee County: February 17 to January 13 (330 days, 0 WNV)
• Wharton County: February 2 to December 25 (326 days, 3 WNV)
• Kenedy County: January 31 to December 22 (325 days, 0 WNV)

West Nile in Liberty County

From 1999 to 2025, CDC ArboNET counted 17 human West Nile cases in Liberty County (16 neuroinvasive) across 7 years. The worst was 2014 with 5; the latest was 2025.

Background: reading the West Nile counts; how the dates are worked out.