Mosquito season in Nassau County, NY: when it starts and ends
Mosquito months in Nassau County
In a normal year mosquito season in Nassau County, NY starts around April 7 and ends around November 8, about 31 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Nassau County, and when
- Start tipping out standing water weekly by March 24.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after November 8.
- 113 West Nile cases since 2016: you should wear EPA-registered repellent at dusk June to August, and check NY spray notices.
Nassau County against the rest of NY
Nassau County has the 4th longest season of 62 NY counties, at 215 days against 218 in New York County and 125 in Franklin County. Its mean temperature is 55.4°F.
- Bronx County: April 6 to November 9 (216 days, 17 WNV)
- Kings County: April 7 to November 9 (216 days, 65 WNV)
- Richmond County: April 7 to November 6 (214 days, 31 WNV)
- Queens County: April 10 to November 7 (211 days, 82 WNV)
West Nile in Nassau County
From 1999 to 2025, CDC ArboNET counted 298 human West Nile cases in Nassau County (218 neuroinvasive) across 24 years. The worst was 2010 with 57; the latest was 2025.
Background: reading the West Nile counts; how the dates are worked out.