Union, WA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Union, a community in Mason County, Washington.
Overnight
51°F
Mostly Cloudy
Mostly cloudy. Low around 51, with temperatures rising to around 53 overnight. West southwest wind around 2 mph.
7-day forecast for Union
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 51°F | Mostly Cloudy | 2 mph WSW | 0% |
| Saturday | 70°F | Partly Sunny | 0 to 3 mph SW | 0% |
| Saturday Night | 51°F | Mostly Clear | 0 to 3 mph W | 0% |
| Sunday | 71°F | Mostly Sunny | 0 to 3 mph ENE | 0% |
| Sunday Night | 50°F | Mostly Clear | 0 to 3 mph NNE | 0% |
| Monday | 69°F | Mostly Sunny | 0 to 3 mph S | 0% |
| Monday Night | 51°F | Partly Cloudy | 0 to 3 mph NNW | 1% |
| Tuesday | 66°F | Partly Sunny | 0 to 5 mph SSW | 1% |
| Tuesday Night | 49°F | Partly Cloudy | 0 to 5 mph W | 4% |
| Wednesday | 65°F | Partly Sunny | 0 to 7 mph SW | 9% |
| Wednesday Night | 49°F | Mostly Cloudy | 0 to 7 mph WNW | 7% |
| Thursday | 62°F | Mostly Cloudy then Slight Chance Light Rain | 0 to 5 mph NE | 22% |
| Thursday Night | 47°F | Slight Chance Light Rain | 0 to 5 mph NNE | 24% |
| Friday | 62°F | Mostly Sunny | 0 to 6 mph ESE | 11% |
Forecast source: National Weather Service (api.weather.gov) for Union (47.348, -123.095). Updated through the day.
Growing snapshot for Union
Last spring frost
Mar 24
First fall frost
Nov 15
Growing season
235 days
Hardiness zone
8b
More local growing data for Union: nearby ZIP 98592 weather · frost dates · planting calendar · Washington frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Cushman Powerhouse #2, Wa (4.7 mi from Union). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.