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

Mosquito months in Henderson County

In a normal year mosquito season in Henderson County, TX starts around March 5 and ends around November 24, about 38 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 Henderson County, and when

• Start tipping out standing water weekly by February 19.
• Book any yard treatment for early March, ahead of the August peak.
• Repellent can go away after November 24.
• 9 West Nile cases since 2016 (last 2025): you should use repellent at dusk May to September, more so if over 60.

Henderson County against the rest of TX

Henderson County has the 137th longest season of 254 TX counties, at 264 days against 365 in Cameron County and 191 in Lipscomb County. Its mean temperature is 65.5°F.

• Cooke County: March 5 to November 24 (264 days, 8 WNV)
• Harrison County: March 5 to November 24 (264 days, 3 WNV)
• Johnson County: March 6 to November 25 (264 days, 17 WNV)
• Madison County: March 2 to November 20 (263 days, 0 WNV)

West Nile in Henderson County

From 1999 to 2025, CDC ArboNET counted 18 human West Nile cases in Henderson County (14 neuroinvasive) across 9 years. The worst was 2016 with 4; the latest was 2025.

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