Mosquito season in Cassia County, ID: when it starts and ends
Mosquito months in Cassia County
In a normal year mosquito season in Cassia County, ID starts around May 3 and ends around October 11, about 23 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Cassia County, and when
- Start tipping out standing water weekly by April 19.
- Book any yard treatment for early May, ahead of the July peak.
- Repellent can go away after October 11.
- 1 West Nile case since 2016 (last 2023): you should use repellent at dusk July to July, more so if over 60.
Cassia County against the rest of ID
Cassia County has the 14th longest season of 44 ID counties, at 161 days against 194 in Canyon County and 85 in Fremont County. Its mean temperature is 47.6°F.
- Washington County: April 28 to October 7 (162 days, 19 WNV)
- Minidoka County: May 2 to October 11 (162 days, 0 WNV)
- Kootenai County: May 1 to October 8 (160 days, 2 WNV)
- Benewah County: May 3 to October 7 (157 days, 0 WNV)
West Nile in Cassia County
From 1999 to 2025, CDC ArboNET counted 6 human West Nile cases in Cassia County (2 neuroinvasive) across 3 years. The worst was 2006 with 4; the latest was 2023.
Background: when the season starts across the US; how the dates are worked out.