Mosquito season in Jefferson County, NE: when it starts and ends
Mosquito months in Jefferson County
In a normal year mosquito season in Jefferson County, NE starts around April 14 and ends around October 23, about 27 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Jefferson County, and when
- Start tipping out standing water weekly by March 31.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 23.
- No West Nile cases since 2016, so bites in Jefferson County are a nuisance; check window screens.
Jefferson County against the rest of NE
Jefferson County has the 13th longest season of 93 NE counties, at 192 days against 200 in Richardson County and 127 in Sioux County. Its mean temperature is 51.6°F.
- Gage County: April 14 to October 23 (192 days, 6 WNV)
- Hamilton County: April 14 to October 22 (192 days, 15 WNV)
- Harlan County: April 13 to October 22 (191 days, 2 WNV)
- Sarpy County: April 14 to October 22 (191 days, 56 WNV)
West Nile in Jefferson County
From 1999 to 2025, CDC ArboNET counted 17 human West Nile cases in Jefferson County (3 neuroinvasive) across 7 years. The worst was 2003 with 10; the latest was 2013.
See how the dates are worked out, and when the season starts across the US.