Union Mill, VA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Union Mill, a community in Fairfax County, Virginia.
This Afternoon
72°F
Sunny
Sunny, with a high near 72. South wind around 7 mph.
7-day forecast for Union Mill
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 72°F | Sunny | 7 mph S | 2% |
| Tonight | 51°F | Mostly Clear then Patchy Fog | 1 to 6 mph S | 2% |
| Wednesday | 75°F | Patchy Fog then Mostly Sunny | 1 to 9 mph S | 3% |
| Wednesday Night | 60°F | Mostly Cloudy then Chance Light Rain | 7 mph S | 29% |
| Thursday | 76°F | Chance Light Rain | 6 to 9 mph S | 48% |
| Thursday Night | 60°F | Light Rain Likely | 2 to 6 mph S | 68% |
| Friday | 72°F | Light Rain Likely | 6 mph S | 74% |
| Friday Night | 52°F | Light Rain Likely | 5 mph N | 62% |
| Saturday | 69°F | Mostly Sunny | 7 mph NW | 12% |
| Saturday Night | 46°F | Partly Cloudy | 5 mph NW | 12% |
| Sunday | 65°F | Mostly Sunny | 6 mph NW | 10% |
| Sunday Night | 44°F | Slight Chance Light Rain | 5 mph NW | 24% |
| Monday | 61°F | Slight Chance Light Rain | 5 to 13 mph NW | 24% |
| Monday Night | 41°F | Slight Chance Light Rain | 8 mph NW | 24% |
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 Nov 3, 2026.