Mosquito season in Crawford County, IA: when it starts and ends

Mosquito months in Crawford County

In a normal year mosquito season in Crawford County, IA starts around April 23 and ends around October 16, about 25 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 Crawford County, and when

• Start tipping out standing water weekly by April 9.
• Book any yard treatment for late April, ahead of the July peak.
• Repellent can go away after October 16.
• 2 West Nile cases since 2016 (last 2025): you should use repellent at dusk July to August, more so if over 60.

Crawford County against the rest of IA

Crawford County has the 65th longest season of 99 IA counties, at 176 days against 198 in Des Moines County and 160 in Worth County. Its mean temperature is 47.5°F.

• Grundy County: April 22 to October 15 (176 days, 2 WNV)
• Pocahontas County: April 22 to October 15 (176 days, 2 WNV)
• Poweshiek County: April 23 to October 16 (176 days, 2 WNV)
• Audubon County: April 22 to October 14 (175 days, 2 WNV)

West Nile in Crawford County

From 1999 to 2025, CDC ArboNET counted 12 human West Nile cases in Crawford County (6 neuroinvasive) across 8 years. The worst was 2014 with 2; the latest was 2025.

Background: when mosquitoes go away for the winter; how the dates are worked out.