Richland, WA 99352 Frost Dates
Richland, WA: when does the frost end?
The last spring frost here typically falls around 04/06, about 221 days from today. Fall's first freeze usually shows up around 10/24, roughly 200 days after the last spring frost.
Zone 7b (5 to 10°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Richland, not a forecast for this year.
Stretching the season past the first frost
With roughly 8 weeks until Richland's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 04/06 isn't a guarantee
04/06 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/22 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/24 and only about 1 year in 10 sees frost after that.
Richland against the rest of the dataset
At roughly 200 frost-free days, Richland places 17,709 of 40,283 ZIP codes in this dataset. Within WA, it ranks 316 of 700.
Learn more
Before leaning on 99352's figures: zone vs. frost date explains why Zone 7b and Richland's frost date answer different questions, while the frost range explains how to read the range around Richland's dates instead of trusting one.