Mosquito season in Castro County, TX: when it starts and ends
Mosquito months in Castro County
In a normal year mosquito season in Castro County, TX starts around April 10 and ends around November 1, about 29 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Castro 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 November 1.
- 3 West Nile cases since 2016 (last 2025): you should use repellent at dusk June to August, more so if over 60.
Castro County against the rest of TX
Castro County has the 247th longest season of 254 TX counties, at 205 days against 365 in Cameron County and 191 in Lipscomb County. Its mean temperature is 56.9°F.
- Armstrong County: April 8 to October 31 (206 days, 1 WNV)
- Moore County: April 10 to November 2 (206 days, 2 WNV)
- Hansford County: April 10 to November 1 (205 days, 4 WNV)
- Parmer County: April 11 to November 2 (205 days, 4 WNV)
West Nile in Castro County
From 1999 to 2025, CDC ArboNET counted 38 human West Nile cases in Castro County (10 neuroinvasive) across 12 years. The worst was 2003 with 19; the latest was 2025.
More: how the dates are worked out · when mosquitoes go away for the winter.