Mosquito season in Jefferson County, AR: when it starts and ends
Mosquito months in Jefferson County
In a normal year mosquito season in Jefferson County, AR starts around March 4 and ends around November 25, about 38 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 February 18.
- Book any yard treatment for early March, ahead of the July peak.
- Repellent can go away after November 25.
- 8 West Nile cases since 2016 (last 2025): you should use repellent at dusk May to September, more so if over 60.
Jefferson County against the rest of AR
Jefferson County has the 9th longest season of 75 AR counties, at 266 days against 274 in Chicot County and 211 in Washington County. Its mean temperature is 63°F.
- Ashley County: March 3 to November 26 (268 days, 0 WNV)
- Drew County: March 4 to November 25 (266 days, 2 WNV)
- Lafayette County: March 5 to November 25 (265 days, 1 WNV)
- Crittenden County: March 4 to November 22 (263 days, 1 WNV)
West Nile in Jefferson County
From 1999 to 2025, CDC ArboNET counted 53 human West Nile cases in Jefferson County (42 neuroinvasive) across 17 years. The worst was 2002 with 9; the latest was 2025.
See how the dates are worked out, and reading the West Nile counts.