Hartline, WA 99135 Frost Dates
Frost dates for Hartline, WA, ZIP 99135
The last spring frost here typically falls around 05/02, about 247 days from today. The first fall frost typically arrives around 10/12, about 162 frost-free days later.
The USDA Plant Hardiness Zone Map puts Hartline in Zone 6b (-5 to 0°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
Zone 6b around Hartline has about 6 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
Why 05/02 isn't a guarantee
05/02 is the middle of 30 years of NOAA records, not a promise. Plant by 04/17 and you're betting against frost in roughly 9 years out of 10. 05/22 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Hartline compares
Hartline's growing season runs about 162 days, ranking 31,881 of 40,283 US ZIP codes measured here, longest to shortest. Within WA, it ranks 566 of 700.
Learn more
the frost range explains how to read the range around Hartline's dates instead of trusting one, and local microclimates explains what one yard in Hartline can differ from the 99135 normal.