Mosquito season in Madison County, IA: when it starts and ends
Mosquito months in Madison County
In a normal year mosquito season in Madison County, IA starts around April 20 and ends around October 15, about 25 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Madison 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 15.
- No West Nile cases since 2016, so bites in Madison County are a nuisance; check window screens.
Madison County against the rest of IA
Madison County has the 50th longest season of 99 IA counties, at 178 days against 198 in Des Moines County and 160 in Worth County. Its mean temperature is 48.1°F.
- Marshall County: April 20 to October 16 (179 days, 1 WNV)
- Jackson County: April 21 to October 17 (179 days, 0 WNV)
- Woodbury County: April 20 to October 15 (178 days, 18 WNV)
- Jones County: April 21 to October 15 (178 days, 1 WNV)
West Nile in Madison County
From 1999 to 2025, CDC ArboNET counted 4 human West Nile cases in Madison County (3 neuroinvasive) across 3 years. The worst was 2005 with 2; the latest was 2012.
More: how the dates are worked out · when the season starts across the US.