Mosquito season in Caddo County, OK: when it starts and ends

Mosquito months in Caddo County

In a normal year mosquito season in Caddo County, OK starts around March 25 and ends around November 10, about 33 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 Caddo County, and when

• Start tipping out standing water weekly by March 11.
• Book any yard treatment for late March, ahead of the July peak.
• Repellent can go away after November 10.
• 2 West Nile cases since 2016 (last 2025): you should use repellent at dusk June to September, more so if over 60.

Caddo County against the rest of OK

Caddo County has the 42nd longest season of 77 OK counties, at 230 days against 271 in Choctaw County and 193 in Cimarron County. Its mean temperature is 60.3°F.

• Garvin County: March 24 to November 9 (230 days, 3 WNV)
• Seminole County: March 24 to November 9 (230 days, 2 WNV)
• Major County: March 26 to November 10 (229 days, 3 WNV)
• Nowata County: March 26 to November 10 (229 days, 0 WNV)

West Nile in Caddo County

From 1999 to 2025, CDC ArboNET counted 6 human West Nile cases in Caddo County (6 neuroinvasive) across 6 years. The worst was 2025 with 1; the latest was 2025.

See how the dates are worked out, and when the season starts across the US.