Mosquito season in Elmore County, ID: when it starts and ends

Mosquito months in Elmore County

In a normal year mosquito season in Elmore County, ID starts around May 30 and ends around September 18, about 16 weeks.

1. Jan
2. Feb
3. Mar
4. Apr
5. May
6. Jun
7. Jul
8. Aug
9. Sep
10. Oct
11. Nov
12. Dec

What to do in Elmore County, and when

• Start tipping out standing water weekly by May 16.
• Book any yard treatment for late May, ahead of the July peak.
• Repellent can go away after September 18.
• 4 West Nile cases since 2016 (last 2019): you should use repellent at dusk July, more so if over 60.

Elmore County against the rest of ID

Elmore County has the 37th longest season of 44 ID counties, at 111 days against 194 in Canyon County and 85 in Fremont County. Its mean temperature is 42.3°F.

• Bear Lake County: May 25 to September 16 (114 days, 0 WNV)
• Camas County: May 28 to September 19 (114 days, 0 WNV)
• Caribou County: May 27 to September 12 (108 days, 0 WNV)
• Custer County: June 2 to September 18 (107 days, 0 WNV)

West Nile in Elmore County

From 1999 to 2025, CDC ArboNET counted 95 human West Nile cases in Elmore County (11 neuroinvasive) across 10 years. The worst was 2006 with 68; the latest was 2019.

Background: reading the West Nile counts; how the dates are worked out.