Union, OH Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Union, a city in Montgomery County, Ohio.
This Afternoon
77°F
Partly Sunny
Partly sunny, with a high near 77. Northeast wind around 9 mph.
7-day forecast for Union
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 77°F | Partly Sunny | 9 mph NE | 1% |
| Tonight | 58°F | Partly Cloudy | 5 to 9 mph NE | 3% |
| Saturday | 81°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 7 mph SE | 53% |
| Saturday Night | 67°F | Showers And Thunderstorms Likely | 7 mph S | 72% |
| Sunday | 81°F | Showers And Thunderstorms Likely | 8 mph W | 56% |
| Sunday Night | 60°F | Showers And Thunderstorms Likely | 10 to 14 mph NE | 56% |
| Monday | 73°F | Showers And Thunderstorms Likely | 10 to 14 mph NE | 55% |
| Monday Night | 56°F | Chance Showers And Thunderstorms | 10 to 15 mph NE | 48% |
| Tuesday | 71°F | Chance Showers And Thunderstorms | 14 mph NE | 37% |
| Tuesday Night | 57°F | Chance Showers And Thunderstorms | 8 to 15 mph NE | 37% |
| Wednesday | 71°F | Chance Rain Showers | 10 mph NE | 30% |
| Wednesday Night | 56°F | Slight Chance Rain Showers | 7 to 12 mph N | 17% |
| Thursday | 71°F | Partly Sunny | 10 mph N | 12% |
| Thursday Night | 55°F | Mostly Cloudy | 6 to 10 mph N | 12% |
Forecast source: National Weather Service (api.weather.gov) for Union (39.907, -84.293). Updated through the day.
Growing snapshot for Union
Last spring frost
Apr 16
First fall frost
Oct 28
Growing season
194 days
Hardiness zone
6a
More local growing data for Union: nearby ZIP 45322 weather · frost dates · planting calendar · Ohio frost dates
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Climate data from the nearest NOAA station, Dayton Intl Ap, Oh (5.8 mi from Union). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.