Mosquito season in Twin Falls County, ID: when it starts and ends
Mosquito months in Twin Falls County
In a normal year mosquito season in Twin Falls County, ID starts around April 26 and ends around October 13, about 24 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Twin Falls County, and when
- Start tipping out standing water weekly by April 12.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 13.
- 10 West Nile cases since 2016: you should wear EPA-registered repellent at dusk July to August, and check ID spray notices.
Twin Falls County against the rest of ID
Twin Falls County has the 7th longest season of 44 ID counties, at 171 days against 194 in Canyon County and 85 in Fremont County. Its mean temperature is 49.1°F.
- Nez Perce County: April 22 to October 14 (175 days, 0 WNV)
- Jerome County: April 25 to October 14 (172 days, 0 WNV)
- Power County: April 26 to October 11 (168 days, 0 WNV)
- Gem County: April 28 to October 12 (167 days, 7 WNV)
West Nile in Twin Falls County
From 1999 to 2025, CDC ArboNET counted 63 human West Nile cases in Twin Falls County (20 neuroinvasive) across 13 years. The worst was 2006 with 38; the latest was 2025.
Background: reading the West Nile counts; how the dates are worked out.