Mosquito season in Sedgwick County, CO: when it starts and ends
Mosquito months in Sedgwick County
In a normal year mosquito season in Sedgwick County, CO starts around April 27 and ends around October 14, about 24 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Sedgwick County, and when
- Start tipping out standing water weekly by April 13.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 14.
- 4 West Nile cases since 2016 (last 2024): you should use repellent at dusk July to August, more so if over 60.
Sedgwick County against the rest of CO
Sedgwick County has the 17th longest season of 64 CO counties, at 170 days against 200 in Mesa County and 69 in Summit County. Its mean temperature is 49.5°F.
- Washington County: April 27 to October 16 (172 days, 6 WNV)
- Morgan County: April 27 to October 15 (171 days, 23 WNV)
- Montezuma County: April 30 to October 17 (170 days, 10 WNV)
- Cheyenne County: April 28 to October 14 (169 days, 0 WNV)
West Nile in Sedgwick County
From 1999 to 2025, CDC ArboNET counted 28 human West Nile cases in Sedgwick County (3 neuroinvasive) across 9 years. The worst was 2003 with 13; the latest was 2024.
See how the dates are worked out, and reading the West Nile counts.