Mosquito season in Natrona County, WY: when it starts and ends
Mosquito months in Natrona County
In a normal year mosquito season in Natrona County, WY starts around May 11 and ends around October 1, about 20 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Natrona County, and when
- Start tipping out standing water weekly by April 27.
- Book any yard treatment for mid May, ahead of the July peak.
- Repellent can go away after October 1.
- 12 West Nile cases since 2016: you should wear EPA-registered repellent at dusk July to July, and check WY spray notices.
Natrona County against the rest of WY
Natrona County has the 12th longest season of 23 WY counties, at 143 days against 163 in Big Horn County and 75 in Teton County. Its mean temperature is 44.4°F.
- Platte County: May 9 to October 1 (145 days, 6 WNV)
- Sweetwater County: May 12 to October 2 (144 days, 0 WNV)
- Washakie County: May 9 to September 28 (142 days, 3 WNV)
- Johnson County: May 11 to September 30 (142 days, 0 WNV)
West Nile in Natrona County
From 1999 to 2025, CDC ArboNET counted 52 human West Nile cases in Natrona County (23 neuroinvasive) across 13 years. The worst was 2003 with 24; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.