Black Diamond, WA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Black Diamond, a city in King County, Washington.
Today
59°F
Mostly Cloudy
Mostly cloudy. High near 59, with temperatures falling to around 54 in the afternoon. North northwest wind around 1 mph.
7-day forecast for Black Diamond
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 59°F | Mostly Cloudy | 1 mph NNW | 4% |
| Tonight | 40°F | Partly Cloudy | 2 mph ESE | 3% |
| Wednesday | 59°F | Mostly Sunny then Slight Chance Light Rain | 2 mph ESE | 15% |
| Wednesday Night | 46°F | Light Rain | 0 to 6 mph SSE | 98% |
| Thursday | 56°F | Chance Light Rain then Partly Sunny | 0 to 5 mph SW | 37% |
| Thursday Night | 44°F | Light Rain | 0 to 5 mph ESE | 78% |
| Friday | 56°F | Light Rain | 1 to 5 mph SSE | 78% |
| Friday Night | 45°F | Chance Light Rain | 3 mph SE | 48% |
| Saturday | 63°F | Chance Light Rain | 0 to 5 mph ESE | 25% |
| Saturday Night | 47°F | Light Rain | 0 to 9 mph SSE | 80% |
| Sunday | 56°F | Light Rain | 1 to 9 mph SSW | 80% |
| Sunday Night | 42°F | Slight Chance Light Rain | 1 to 5 mph SE | 20% |
| Monday | 57°F | Chance Light Rain | 0 to 5 mph SE | 49% |
| Monday Night | 45°F | Light Rain Likely | 0 to 6 mph SE | 68% |
Forecast source: National Weather Service (api.weather.gov) for Black Diamond (47.315, -122.018). Updated through the day.
Growing snapshot for Black Diamond
Last spring frost
Apr 20
First fall frost
Oct 25
Growing season
187 days
Hardiness zone
8b
More local growing data for Black Diamond: nearby ZIP 98010 weather · frost dates · planting calendar · Washington frost dates
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Climate data from the nearest NOAA station, Landsburg, Wa (4.6 mi from Black Diamond). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 3, 2026.