Union Mill, VA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Union Mill, a community in Fairfax County, Virginia.
Today
86°F
Partly Sunny
Partly sunny, with a high near 86. East wind 3 to 7 mph.
7-day forecast for Union Mill
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 86°F | Partly Sunny | 3 to 7 mph E | 8% |
| Tonight | 70°F | Slight Chance Showers And Thunderstorms then Showers And Thunderstorms Likely | 1 to 7 mph E | 72% |
| Wednesday | 86°F | Showers And Thunderstorms Likely | 1 to 7 mph SE | 67% |
| Wednesday Night | 72°F | Showers And Thunderstorms Likely then Chance Showers And Thunderstorms | 3 to 7 mph S | 56% |
| Thursday | 90°F | Mostly Sunny | 6 to 10 mph S | 13% |
| Thursday Night | 72°F | Partly Cloudy | 5 to 9 mph SW | 14% |
| Friday | 90°F | Mostly Sunny then Chance Showers And Thunderstorms | 7 mph SW | 39% |
| Friday Night | 71°F | Chance Showers And Thunderstorms | 2 to 6 mph SW | 44% |
| Saturday | 89°F | Partly Sunny then Chance Showers And Thunderstorms | 2 to 6 mph SW | 51% |
| Saturday Night | 70°F | Chance Showers And Thunderstorms | 1 to 6 mph SW | 51% |
| Sunday | 89°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 1 to 5 mph W | 20% |
| Sunday Night | 72°F | Slight Chance Showers And Thunderstorms then Partly Cloudy | 1 to 5 mph SW | 20% |
| Monday | 91°F | Mostly Sunny | 1 to 6 mph W | 10% |
| Monday Night | 72°F | Partly Cloudy | 5 mph W | 14% |
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 Aug 4, 2026.