Rock Island, WA 98850 Frost Dates
Rock Island, WA: when does the frost end?
Around 04/08 is the usual last spring frost, about 223 days away. Fall's first freeze usually shows up around 10/24, roughly 200 days after the last spring frost.
Rock Island sits in USDA Zone 7a (0 to 5°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
Stretching the season past the first frost
With roughly 8 weeks until Rock Island's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
The actual range around Rock Island's last frost
04/08 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/20 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/23 and only about 1 year in 10 sees frost after that.
Rock Island against the rest of the dataset
About 200 days separate Rock Island's last and first frost, putting it 17,825 of 40,283 ZIP codes nationally. Within WA, it ranks 325 of 700.
Learn more
Before leaning on 98850's figures: the frost range explains how to read the range around Rock Island's dates instead of trusting one, while local microclimates explains what one yard in Rock Island can differ from the 98850 normal.