Mosquito season in Charles County, MD: when it starts and ends
Mosquito months in Charles County
In a normal year mosquito season in Charles County, MD starts around April 2 and ends around November 6, about 31 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Charles County, and when
- Start tipping out standing water weekly by March 19.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after November 6.
- 2 West Nile cases since 2016 (last 2025): you should use repellent at dusk June to August, more so if over 60.
Charles County against the rest of MD
Charles County has the 17th longest season of 24 MD counties, at 218 days against 235 in Wicomico County and 175 in Garrett County. Its mean temperature is 56.6°F.
- Prince George's County: April 1 to November 5 (219 days, 17 WNV)
- Calvert County: April 2 to November 6 (218 days, 1 WNV)
- Kent County: April 2 to November 6 (218 days, 2 WNV)
- Cecil County: April 4 to November 4 (215 days, 5 WNV)
West Nile in Charles County
From 1999 to 2025, CDC ArboNET counted 4 human West Nile cases in Charles County (2 neuroinvasive) across 4 years. The worst was 2025 with 1; the latest was 2025.
See how the dates are worked out, and when the season starts across the US.