Mosquito season in Jefferson County, TN: when it starts and ends

Mosquito months in Jefferson County

In a normal year mosquito season in Jefferson County, TN starts around March 22 and ends around November 7, about 33 weeks.

1. Jan
2. Feb
3. Mar
4. Apr
5. May
6. Jun
7. Jul
8. Aug
9. Sep
10. Oct
11. Nov
12. Dec

What to do in Jefferson County, and when

• Start tipping out standing water weekly by March 8.
• Book any yard treatment for late March, ahead of the July peak.
• Repellent can go away after November 7.
• 2 West Nile cases since 2016 (last 2023): you should use repellent at dusk June to August, more so if over 60.

Jefferson County against the rest of TN

Jefferson County has the 26th longest season of 95 TN counties, at 230 days against 252 in Hamilton County and 186 in Carter County. Its mean temperature is 57.2°F.

• Loudon County: March 25 to November 12 (232 days, 0 WNV)
• Cocke County: March 24 to November 10 (231 days, 0 WNV)
• Madison County: March 22 to November 7 (230 days, 1 WNV)
• Obion County: March 22 to November 7 (230 days, 1 WNV)

West Nile in Jefferson County

From 1999 to 2025, CDC ArboNET counted 2 human West Nile cases in Jefferson County (2 neuroinvasive) across 2 years. The worst was 2023 with 1; the latest was 2023.

See how the dates are worked out, and when mosquitoes go away for the winter.