St. Helena, CA 94576 Frost Dates
When can you plant in St. Helena, CA?
Around 04/07 is the usual last spring frost, about 222 days away. The first fall frost typically arrives around 12/05, about 245 frost-free days later.
Zone 9b (25 to 30°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
About 14 weeks of growing season left in St. Helena before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
How much risk comes with planting early here
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
St. Helena's growing season runs about 245 days, ranking 8,016 of 40,283 US ZIP codes measured here, longest to shortest. Within CA, it ranks 2,106 of 2,555.
Learn more
the frost range covers how to read the range around St. Helena's dates instead of trusting one. local microclimates covers what one yard in St. Helena can differ from the 94576 normal.