Mosquito season in Navajo County, AZ: when it starts and ends
Mosquito months in Navajo County
In a normal year mosquito season in Navajo County, AZ starts around May 1 and ends around October 20, about 25 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Navajo County, and when
- Start tipping out standing water weekly by April 17.
- Book any yard treatment for early May, ahead of the July peak.
- Repellent can go away after October 20.
- 7 West Nile cases since 2016 (last 2023): you should use repellent at dusk July to August, more so if over 60.
Navajo County against the rest of AZ
Navajo County has the 13th longest season of 15 AZ counties, at 172 days against 364 in Maricopa County and 150 in Coconino County. Its mean temperature is 53.2°F.
- Greenlee County: April 21 to October 28 (190 days, 0 WNV)
- Mohave County: April 30 to October 23 (176 days, 4 WNV)
- Apache County: May 7 to October 17 (163 days, 4 WNV)
- Coconino County: May 15 to October 12 (150 days, 0 WNV)
West Nile in Navajo County
From 1999 to 2025, CDC ArboNET counted 11 human West Nile cases in Navajo County (8 neuroinvasive) across 8 years. The worst was 2019 with 4; the latest was 2023.
Background: reading the West Nile counts; how the dates are worked out.