Black Diamond, WA 98051 Frost Dates
Black Diamond, WA: when does the frost end?
Typically, the last spring freeze lands around 04/20, roughly 235 days out. Fall's first freeze usually shows up around 10/25, roughly 187 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Black Diamond in Zone 8b (15 to 20°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
With roughly 8 weeks until Black Diamond's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
The actual range around Black Diamond's last frost
04/20 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/31 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/10 and only about 1 year in 10 sees frost after that.
Black Diamond against the rest of the dataset
About 187 days separate Black Diamond's last and first frost, putting it 22,346 of 40,283 ZIP codes nationally. Within WA, it ranks 422 of 700.
Learn more
Before leaning on 98051's figures: local microclimates explains what one yard in Black Diamond can differ from the 98051 normal, while zone vs. frost date explains why Zone 8b and Black Diamond's frost date answer different questions.