Frost dates / California / Petaluma

Frost dates in Petaluma, CA

The station on this page is PETALUMA AP, CA US (USC00046826), 1.6 miles from the city point. Population in the Census 2024 estimate is 59,393.

Zone 9bUSDA average annual extreme minimum 25°F to 30°F, from ZIP 94954 (3.9 miles from the city point used on this page).

Median last 32°F is February 28. Median first 32°F is November 25. The 50% growing-season length is 271 days. The green band runs from the median last frost to the median first frost. Thin ticks mark the 10%, 50%, and 90% dates.

Outside the median season Growing seasonTicks: 10%, 50%, and 90%

Last 32°F in spring

NCEI’s probability is the chance the last spring minimum of 32°F or lower occurs on or after the date.

Probability	Date	How to read it
90%	January 24	Earlier date. A last 32°F on or after this day is common.
50%	February 28	Median.
10%	April 6	Later date. A last 32°F on or after this day is uncommon.

First 32°F in fall

NCEI’s probability is the chance the first autumn minimum of 32°F or lower occurs on or before the date.

Probability	Date	How to read it
10%	November 9	Earlier date. A first 32°F on or before this day is uncommon.
50%	November 25	Median.
90%	December 16	Later date. A first 32°F on or before this day is common.

32°F growing-season length

Days between the last spring 32°F and the first autumn 32°F. The figure is a length the season meets or exceeds at that probability, from NCEI, not a subtraction done on this site.

Probability the season is at least this long	Days
10%	313
50%	271
90%	230

28°F threshold

	10%	50%	90%
Last, on or after	February 24	January 17	December 17
First, on or before	November 20	December 9	January 12
Season at least	365 days	331 days	289 days

36°F threshold

	10%	50%	90%
Last, on or after	April 27	April 6	March 7
First, on or before	October 27	November 10	November 28
Season at least	249 days	218 days	193 days

Station PETALUMA AP, CA US (USC00046826). Completeness flag S, 26 years used for the 32°F dates. NCEI’s annual probability of at least one day at or below 32°F is 99.5%. Freeze dates are conditional on that threshold occurring. Elevation 6.1 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.

Planting calendar for Petaluma · Zone 9b

Check a crop against this station

Petaluma, CA

Zone 9bAverage annual extreme minimum 25°F to 30°F

Outside the median season Growing seasonTicks: 10%, 50%, and 90%

California. Nearest qualified station: PETALUMA AP, CA US (USC00046826), 1.6 miles. Median last 32°F February 28. Median first 32°F November 25. The 50% growing-season length is 271 days.

Open the ZIP page · Crop guides for California

32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	April 6	February 28	January 24
First 32°F on or before	November 9	November 25	December 16

Column order matches the NCEI file: for the last freeze, 10% is the later date and 90% is the earlier date. How to read the probabilities.

A wall calendar surrounded by vegetables, herbs, seed packets, and watering cans.

Planting calendar

Windows below are from UC ANR, UC Master Gardener Program, Time of planting, retrieved 2026-10-10. North and North Coast = Monterey County north; South Coast = San Luis Obispo County south; Interior Valleys = Sacramento, San Joaquin, and similar valleys; Desert Valleys = Imperial and Coachella Valleys. Source line on the page: California Master Gardener Handbook, Table 13.2, Adapted from Vegetable Gardening Illustrated 1994.

Crop

Date checks use your device’s calendar and appear after the page loads.