Mosquito season in Osceola County, IA: when it starts and ends
Mosquito months in Osceola County
In a normal year mosquito season in Osceola County, IA starts around April 28 and ends around October 11, about 24 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Osceola County, and when
- Start tipping out standing water weekly by April 14.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 11.
- 2 West Nile cases since 2016 (last 2024): you should use repellent at dusk July to July, more so if over 60.
Osceola County against the rest of IA
Osceola County has the 97th longest season of 99 IA counties, at 166 days against 198 in Des Moines County and 160 in Worth County. Its mean temperature is 44.8°F.
- Chickasaw County: April 27 to October 10 (166 days, 2 WNV)
- Emmet County: April 27 to October 10 (166 days, 2 WNV)
- Howard County: April 29 to October 10 (164 days, 0 WNV)
- Worth County: April 30 to October 7 (160 days, 0 WNV)
West Nile in Osceola County
From 1999 to 2025, CDC ArboNET counted 4 human West Nile cases in Osceola County (3 neuroinvasive) across 3 years. The worst was 2003 with 2; the latest was 2024.
Background: when mosquitoes go away for the winter; how the dates are worked out.