Mosquito season in Mahaska County, IA: when it starts and ends
Mosquito months in Mahaska County
In a normal year mosquito season in Mahaska County, IA starts around April 15 and ends around October 21, about 27 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Mahaska County, and when
- Start tipping out standing water weekly by April 1.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 21.
- 1 West Nile case since 2016 (last 2025): you should use repellent at dusk June to August, more so if over 60.
Mahaska County against the rest of IA
Mahaska County has the 12th longest season of 99 IA counties, at 190 days against 198 in Des Moines County and 160 in Worth County. Its mean temperature is 50.1°F.
- Page County: April 14 to October 21 (190 days, 2 WNV)
- Scott County: April 14 to October 21 (190 days, 3 WNV)
- Montgomery County: April 15 to October 22 (190 days, 3 WNV)
- Polk County: April 14 to October 20 (189 days, 25 WNV)
West Nile in Mahaska County
From 1999 to 2025, CDC ArboNET counted 6 human West Nile cases in Mahaska County (4 neuroinvasive) across 4 years. The worst was 2015 with 2; the latest was 2025.
More: how the dates are worked out · when mosquitoes go away for the winter.