Black Diamond, WA Weather & Growing Conditions

Local forecast, frost dates, hardiness zone and planting guidance for Black Diamond, a city in King County, Washington.

Tonight

49°F

Mostly Cloudy

Mostly cloudy, with a low around 49. Southeast wind around 1 mph.

7-day forecast for Black Diamond

When	Temp	Forecast	Wind	Precip
Tonight	49°F	Mostly Cloudy	1 mph SE	0%
Saturday	72°F	Partly Sunny	1 mph NNW	0%
Saturday Night	51°F	Mostly Clear	1 mph NE	0%
Sunday	74°F	Mostly Sunny	1 mph NNW	0%
Sunday Night	50°F	Mostly Clear	1 mph NNE	0%
Monday	71°F	Mostly Sunny	2 mph NW	0%
Monday Night	50°F	Partly Cloudy	2 mph ENE	0%
Tuesday	67°F	Partly Sunny	1 mph WSW	1%
Tuesday Night	48°F	Mostly Cloudy	1 mph S	4%
Wednesday	66°F	Partly Sunny	1 mph W	14%
Wednesday Night	49°F	Mostly Cloudy	1 mph ENE	14%
Thursday	64°F	Mostly Cloudy then Slight Chance Light Rain	2 mph NNE	19%
Thursday Night	48°F	Slight Chance Light Rain	2 mph ENE	19%
Friday	62°F	Slight Chance Light Rain	2 mph WNW	16%

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

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 Sep 19, 2026.