Mosquito season in Cass County, NE: when it starts and ends
Mosquito months in Cass County
In a normal year mosquito season in Cass County, NE starts around April 13 and ends around October 22, about 27 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Cass County, and when
- Start tipping out standing water weekly by March 30.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 22.
- 12 West Nile cases since 2016: you should wear EPA-registered repellent at dusk June to August, and check NE spray notices.
Cass County against the rest of NE
Cass County has the 7th longest season of 93 NE counties, at 192 days against 200 in Richardson County and 127 in Sioux County. Its mean temperature is 51.1°F.
- Thayer County: April 13 to October 23 (193 days, 7 WNV)
- Adams County: April 13 to October 22 (192 days, 17 WNV)
- Clay County: April 13 to October 23 (192 days, 4 WNV)
- Hall County: April 13 to October 22 (192 days, 37 WNV)
West Nile in Cass County
From 1999 to 2025, CDC ArboNET counted 18 human West Nile cases in Cass County (11 neuroinvasive) across 9 years. The worst was 2018 with 9; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.