Frost dates / California / San Ramon
Frost dates in San Ramon, CA
The station on this page is MT DIABLO JUNCTION, CA US (USC00045915), 7.9 miles from the city point. Population in the Census 2024 estimate is 85,924.
Zone 9bUSDA average annual extreme minimum 25°F to 30°F, from ZIP 94582 (0.9 miles from the city point used on this page).
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 12 | Earlier date. A last 32°F on or after this day is common. |
| 50% | March 8 | Median. |
| 10% | April 15 | 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 23 | Earlier date. A first 32°F on or before this day is uncommon. |
| 50% | December 22 | Median. |
| 90% | February 11 | 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% | 343 |
| 50% | 282 |
| 90% | 238 |
28°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | March 23 | February 8 | December 21 |
| First, on or before | December 8 | January 16 | March 3 |
| Season at least | 365 days | 364 days | 286 days |
36°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | May 20 | April 19 | March 16 |
| First, on or before | November 6 | November 29 | December 20 |
| Season at least | 264 days | 221 days | 183 days |
Station MT DIABLO JUNCTION, CA US (USC00045915). Completeness flag R, 25 years used for the 32°F dates. NCEI’s annual probability of at least one day at or below 32°F is 95.9%. Freeze dates are conditional on that threshold occurring. Elevation 661.4 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 San Ramon · Zone 9b
Check a crop against this station
San Ramon, 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: MT DIABLO JUNCTION, CA US (USC00045915), 7.9 miles. Median last 32°F March 8. Median first 32°F December 22. The 50% growing-season length is 282 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 15 | March 8 | January 12 |
| First 32°F on or before | November 23 | December 22 | February 11 |
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.
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.
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