Best days to spray weeds, by city
Weed killer: 3–10 mph wind, 45–85°F, 4 rain-free hours after. Pick a city for a live 7-day verdict from the National Weather Service forecast and the months that usually work there.
Alabama
Arizona
Arkansas
California
Colorado
Connecticut
District of Columbia
Florida
Georgia
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Nebraska
Nevada
New Mexico
Oklahoma
Oregon
Rhode Island
South Carolina
Virginia
Washington
Wisconsin
The rules Fairsky uses
- Needs 2 hours in a row of daylight.
- Air at least 45°F.
- No hotter than 85°F (86–90°F is borderline).
- Wind between 3 and 10 mph (calmer air can mean a temperature inversion that carries drift).
- Gusts at or under 15 mph. (Fairsky default)
- Rain chance at or below 20%. (Fairsky default)
- No rain for 4 hours after you finish.
Your product's label wins.
Sources: NC State Extension: spray drift and wind speed · UNL CropWatch: avoiding herbicide drift · UNL CropWatch: managing applications to avoid drift · Rutgers: herbicide drift and temperature · Roundup concentrate label (rainfast time)
The app covers 47 activities in all: see every activity and its rules.
Fairsky is not a substitute for official warnings. For warnings, go to weather.gov.
Live forecasts: National Weather Service / NOAA (public domain), fetched by your browser. Climate averages: NOAA NCEI U.S. Climate Normals, 1991–2020 (public domain). Activity thresholds: product data sheets, ACI and university extension guidance, linked on each page; your product’s label wins.