St. Helena, CA 94567 Frost Dates
Frost dates for St. Helena, CA, ZIP 94567
The last spring frost here typically falls around 04/07, about 222 days from today. The first fall frost typically arrives around 12/05, about 245 frost-free days later.
Zone 9a (20 to 25°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 St. Helena, not a forecast for this year.
What to do before the first frost
Zone 9a around St. Helena has about 14 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.
The actual range around St. Helena's last frost
04/07 is the middle of 30 years of NOAA records, not a promise. Plant by 02/23 and you're betting against frost in roughly 9 years out of 10. 04/30 is the safer bet, historically only a 1-in-10 chance of frost that late.
How St. Helena compares
About 245 days separate St. Helena's last and first frost, putting it 8,015 of 40,283 ZIP codes nationally. Within CA, it ranks 2,105 of 2,555.
Learn more
zone vs. frost date explains why Zone 9a and St. Helena's frost date answer different questions, and the frost range explains how to read the range around St. Helena's dates instead of trusting one.