Mosquito season in Harford County, MD: when it starts and ends
Mosquito months in Harford County
In a normal year mosquito season in Harford County, MD starts around April 5 and ends around November 2, about 30 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Harford County, and when
- Start tipping out standing water weekly by March 22.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after November 2.
- 9 West Nile cases since 2016 (last 2024): you should use repellent at dusk June to August, more so if over 60.
Harford County against the rest of MD
Harford County has the 20th longest season of 24 MD counties, at 211 days against 235 in Wicomico County and 175 in Garrett County. Its mean temperature is 54.9°F.
- Kent County: April 2 to November 6 (218 days, 2 WNV)
- Cecil County: April 4 to November 4 (215 days, 5 WNV)
- Washington County: April 6 to October 31 (208 days, 3 WNV)
- Allegany County: April 6 to October 28 (205 days, 0 WNV)
West Nile in Harford County
From 1999 to 2025, CDC ArboNET counted 20 human West Nile cases in Harford County (12 neuroinvasive) across 11 years. The worst was 2018 with 5; the latest was 2024.
See how the dates are worked out, and reading the West Nile counts.