Mosquito season in Clark County, ID: when it starts and ends
Mosquito months in Clark County
In a normal year mosquito season in Clark County, ID starts around May 10 and ends around September 30, about 20 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Clark County, and when
- Start tipping out standing water weekly by April 26.
- Book any yard treatment for early May, ahead of the July peak.
- Repellent can go away after September 30.
- No West Nile cases since 2016, so bites in Clark County are a nuisance; check window screens.
Clark County against the rest of ID
Clark County has the 27th longest season of 44 ID counties, at 143 days against 194 in Canyon County and 85 in Fremont County. Its mean temperature is 43°F.
- Shoshone County: May 8 to September 30 (145 days, 0 WNV)
- Lewis County: May 13 to October 4 (144 days, 1 WNV)
- Butte County: May 13 to October 1 (141 days, 0 WNV)
- Jefferson County: May 14 to September 21 (130 days, 0 WNV)
West Nile in Clark County
CDC ArboNET lists no human West Nile cases for Clark County from 1999 to 2025, though virus turned up in birds, mosquitoes or horses in 2 of those years.
More: how the dates are worked out · when mosquitoes go away for the winter.