Mosquito season in Yuma County, AZ: when it starts and ends
Mosquito months in Yuma County
In a normal year mosquito season in Yuma County, AZ starts around January 23 and ends around December 11, about 46 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Yuma County, and when
- Start tipping out standing water weekly by January 9.
- Book any yard treatment for late January, ahead of the August peak.
- Repellent can go away after December 11.
- 8 West Nile cases since 2016 (last 2023): you should use repellent at dusk April to October, more so if over 60.
Yuma County against the rest of AZ
Yuma County has the 4th longest season of 15 AZ counties, at 322 days against 364 in Maricopa County and 150 in Coconino County. Its mean temperature is 73.1°F.
- Pinal County: January 8 to December 26 (352 days, 154 WNV)
- La Paz County: January 7 to December 21 (348 days, 2 WNV)
- Gila County: February 2 to December 7 (308 days, 9 WNV)
- Santa Cruz County: February 23 to November 30 (280 days, 2 WNV)
West Nile in Yuma County
From 1999 to 2025, CDC ArboNET counted 11 human West Nile cases in Yuma County (7 neuroinvasive) across 7 years. The worst was 2023 with 3; the latest was 2023.
See how the dates are worked out, and reading the West Nile counts.