Mill Valley, CA 94161 Frost Dates
Mill Valley, CA: when does the frost end?
Around 12/30 is the usual last spring frost, about 124 days away. Fall's first freeze usually shows up around 12/25, roughly 365 days after the last spring frost.
Mill Valley sits in USDA Zone 10b (35 to 40°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 17 weeks until Mill Valley's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 12/30 isn't a guarantee
12/30 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/13 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 12/02 and only about 1 year in 10 sees frost after that.
Mill Valley against the rest of the dataset
Mill Valley's growing season runs about 365 days, ranking 1,666 of 40,283 US ZIP codes measured here, longest to shortest. Within CA, it ranks 811 of 2,555.
Learn more
Before leaning on 94161's figures: zone vs. frost date explains why Zone 10b and Mill Valley's frost date answer different questions, while the frost range explains how to read the range around Mill Valley's dates instead of trusting one.