Union Mill, VA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Union Mill, a community in Fairfax County, Virginia.
Tonight
63°F
Mostly Cloudy
Mostly cloudy, with a low around 63. North wind around 8 mph.
7-day forecast for Union Mill
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 63°F | Mostly Cloudy | 8 mph N | 10% |
| Saturday | 79°F | Partly Sunny | 7 mph E | 10% |
| Saturday Night | 67°F | Mostly Cloudy | 7 mph SE | 10% |
| Sunday | 83°F | Partly Sunny then Chance Showers And Thunderstorms | 5 to 13 mph S | 42% |
| Sunday Night | 66°F | Showers And Thunderstorms Likely | 3 to 9 mph NW | 59% |
| Monday | 75°F | Chance Rain Showers | 7 to 10 mph NE | 41% |
| Monday Night | 62°F | Rain Showers Likely | 5 to 9 mph NE | 58% |
| Tuesday | 67°F | Rain Showers Likely | 10 mph NE | 62% |
| Tuesday Night | 57°F | Rain Showers Likely | 10 mph NE | 62% |
| Wednesday | 62°F | Chance Rain Showers | 12 mph NE | 54% |
| Wednesday Night | 56°F | Chance Showers And Thunderstorms | 7 to 10 mph NE | 51% |
| Thursday | 64°F | Chance Showers And Thunderstorms | 10 mph N | 51% |
| Thursday Night | 55°F | Chance Showers And Thunderstorms | 5 to 8 mph N | 34% |
| Friday | 68°F | Slight Chance Rain Showers | 7 to 10 mph N | 23% |
Forecast source: National Weather Service (api.weather.gov) for Union Mill (38.801, -77.387). Updated through the day.
Growing snapshot for Union Mill
Last spring frost
Apr 12
First fall frost
Oct 27
Growing season
197 days
Hardiness zone
7b
More local growing data for Union Mill: nearby ZIP 20124 weather · frost dates · planting calendar · Virginia frost dates
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Climate data from the nearest NOAA station, Manassas, Va (6.4 mi from Union Mill). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.