Mosquito season in Monona County, IA: when it starts and ends
Mosquito months in Monona County
In a normal year mosquito season in Monona County, IA starts around April 20 and ends around October 17, about 26 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Monona County, and when
- Start tipping out standing water weekly by April 6.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 17.
- 2 West Nile cases since 2016 (last 2018): you should use repellent at dusk June to August, more so if over 60.
Monona County against the rest of IA
Monona County has the 47th longest season of 99 IA counties, at 180 days against 198 in Des Moines County and 160 in Worth County. Its mean temperature is 48°F.
- Carroll County: April 20 to October 18 (181 days, 3 WNV)
- Greene County: April 20 to October 17 (180 days, 2 WNV)
- Marshall County: April 20 to October 16 (179 days, 1 WNV)
- Jackson County: April 21 to October 17 (179 days, 0 WNV)
West Nile in Monona County
From 1999 to 2025, CDC ArboNET counted 18 human West Nile cases in Monona County (7 neuroinvasive) across 8 years. The worst was 2003 with 7; the latest was 2018.
Background: when mosquitoes go away for the winter; how the dates are worked out.