Mosquito season in Pinal County, AZ: when it starts and ends

Mosquito months in Pinal County

In a normal year mosquito season in Pinal County, AZ starts around January 8 and ends around December 26, about 50 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 Pinal County, and when

• Start tipping out standing water weekly by December 25.
• Book any yard treatment for early January, ahead of the July peak.
• Repellent can go away after December 26.
• 154 West Nile cases since 2016: you should wear EPA-registered repellent at dusk May to October, and check AZ spray notices.

Pinal County against the rest of AZ

Pinal County has the 2nd longest season of 15 AZ counties, at 352 days against 364 in Maricopa County and 150 in Coconino County. Its mean temperature is 71.6°F.

• Maricopa County: January 5 to January 4 (364 days, 1,999 WNV)
• La Paz County: January 7 to December 21 (348 days, 2 WNV)
• Yuma County: January 23 to December 11 (322 days, 8 WNV)

West Nile in Pinal County

From 1999 to 2025, CDC ArboNET counted 232 human West Nile cases in Pinal County (171 neuroinvasive) across 20 years. The worst was 2021 with 121; the latest was 2025.

See how the dates are worked out, and where mosquitoes never stop.