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

Mosquito months in Knox County

In a normal year mosquito season in Knox County, TN starts around March 31 and ends around November 6, about 31 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 Knox County, and when

• Start tipping out standing water weekly by March 17.
• Book any yard treatment for late March, ahead of the July peak.
• Repellent can go away after November 6.
• 4 West Nile cases since 2016 (last 2025): you should use repellent at dusk June to September, more so if over 60.

Knox County against the rest of TN

Knox County has the 55th longest season of 95 TN counties, at 220 days against 252 in Hamilton County and 186 in Carter County. Its mean temperature is 58.7°F.

• Cheatham County: March 29 to November 5 (221 days, 0 WNV)
• Maury County: March 29 to November 5 (221 days, 0 WNV)
• Bledsoe County: March 29 to November 3 (219 days, 0 WNV)
• Chester County: March 30 to November 4 (219 days, 0 WNV)

West Nile in Knox County

From 1999 to 2025, CDC ArboNET counted 10 human West Nile cases in Knox County (6 neuroinvasive) across 8 years. The worst was 2017 with 2; the latest was 2025.

More: how the dates are worked out · reading the West Nile counts.