Mosquito season in Macoupin County, IL: when it starts and ends
Mosquito months in Macoupin County
In a normal year mosquito season in Macoupin County, IL starts around April 4 and ends around October 29, about 30 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Macoupin County, and when
- Start tipping out standing water weekly by March 21.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after October 29.
- 3 West Nile cases since 2016 (last 2025): you should use repellent at dusk June to August, more so if over 60.
Macoupin County against the rest of IL
Macoupin County has the 39th longest season of 102 IL counties, at 207 days against 232 in Pulaski County and 174 in Boone County. Its mean temperature is 53.5°F.
- Pike County: April 4 to October 30 (208 days, 0 WNV)
- Clark County: April 5 to October 30 (208 days, 0 WNV)
- Christian County: April 5 to October 29 (207 days, 0 WNV)
- Shelby County: April 5 to October 29 (207 days, 0 WNV)
West Nile in Macoupin County
From 1999 to 2025, CDC ArboNET counted 14 human West Nile cases in Macoupin County (7 neuroinvasive) across 8 years. The worst was 2002 with 6; the latest was 2025.
Background: when the season starts across the US; how the dates are worked out.