Rio Dell, CA 95545 Frost Dates
Frost dates for Rio Dell, CA, ZIP 95545
Around 03/04 is the usual last spring frost, about 188 days away. The first fall frost typically arrives around 11/22, about 264 frost-free days later.
The USDA Plant Hardiness Zone Map puts Rio Dell in Zone 9b (25 to 30°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 9b around Rio Dell has about 12 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 03/04 isn't a guarantee
03/04 is the middle of 30 years of NOAA records, not a promise. Plant by 01/27 and you're betting against frost in roughly 9 years out of 10. 04/08 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Rio Dell compares
Rio Dell's growing season runs about 264 days, ranking 6,065 of 40,283 US ZIP codes measured here, longest to shortest. Within CA, it ranks 2,006 of 2,555.
Learn more
zone vs. frost date explains why Zone 9b and Rio Dell's frost date answer different questions, and the frost range explains how to read the range around Rio Dell's dates instead of trusting one.