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Will it freeze in San Ramon in the next 7 nights?
No overnight lows at or below 32°F are forecast in San Ramon during the next 7 nights in the available NWS frost forecast.
Tonight: forecast low 46°F. Above 36°F.
NWS forecast period: Thu, Nov 5, 6:00 PM PST to Fri, Nov 6, 6:00 AM PST.
No nights at or below 36°F in the National Weather Service forecast for the next 7 nights.
- Tonight 46°F Above 36°F · Mostly Clear
- Fri, Nov 6 46°F Above 36°F · Mostly Clear
- Sat, Nov 7 48°F Above 36°F · Mostly Clear then Patchy Fog
- Sun, Nov 8 49°F Above 36°F · Partly Cloudy
- Mon, Nov 9 48°F Above 36°F · Mostly Clear then Patchy Fog
- Tue, Nov 10 50°F Above 36°F · Partly Cloudy then Slight Chance Light Rain
- Wed, Nov 11 49°F Above 36°F · Slight Chance Light Rain
Overnight lows from the National Weather Service forecast for this location. This covers the available forecast window, not the first freeze of the whole season. Frost can form above 32°F on clear, calm nights.
Frost and freeze probabilities
Freeze dates shift from year to year. Spring percentages describe the chance of a freeze after the stated date; fall percentages describe the chance of a freeze by that date. The 10% spring date is the cautious one: a later freeze happens about 1 year in 10.
These dates describe historical probabilities, not this year’s forecast or the earliest and latest possible freezes. Different weather stations or probability thresholds can produce different published dates for the same city.
Average first hard freeze in San Ramon
The median first fall hard-freeze date (28°F) is January 16, from NOAA’s 1991–2020 Climate Normals at Mt Diablo Junction. This is the 50% probability date, not a forecast for this year.
| Temperature | Last spring date 90% · 50% · 10% chance of a later freeze | First fall date 10% · 50% · 90% chance of an earlier freeze | Season |
|---|---|---|---|
| 36°F frost possible | Mar 16 · Apr 19 · May 20 | Nov 6 · Nov 29 · Dec 20 | 221 days |
| 32°F freeze | Jan 12 · Mar 8 · Apr 15 | Nov 23 · Dec 22 · Feb 11 | 282 days |
| 28°F hard freeze | Dec 21 · Feb 8 · Mar 23 | Dec 8 · Jan 16 · Mar 3 | 364 days |
Average high temperature by month
1991–2020 normals at Mt Diablo Junction
Average low temperature by month
Months with lows near or below freezing carry frost risk
Where these frost dates come from
The frost dates for San Ramon, CA come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Mt Diablo Junction (station USC00045915, elevation 2,170 ft), 7.9 mi from San Ramon. Local conditions (valleys, hilltops, distance to water, city heat) can shift frost dates by days or weeks. The hardiness zone is from the 2023 USDA Plant Hardiness Zone Map (USDA ARS and Oregon State University PRISM). See our methodology.
Frost dates near San Ramon
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Danville, CA | 3.7 mi | Mar 8 | Dec 22 |
| Dublin, CA | 3.7 mi | Feb 15 | Dec 2 |
| Pleasanton, CA | 7.5 mi | Feb 15 | Dec 2 |
| Livermore, CA | 11 mi | Feb 15 | Dec 2 |
| Walnut Creek, CA | 11 mi | Jan 7 | Dec 19 |
| Moraga, CA | 12 mi | rare | rare |
| Clayton, CA | 12 mi | Mar 8 | Dec 22 |
| Union City, CA | 12 mi | Jan 7 | Dec 22 |
| San Leandro, CA | 13 mi | Jan 7 | Dec 23 |
| Hayward, CA | 14 mi | rare | rare |
Frequently asked questions
When is the last frost in San Ramon?
On average, the last spring frost (32°F) in San Ramon is around March 8. In about 1 year in 10 it comes after April 15, and in 9 years in 10 it comes after January 12.
When is the first frost in San Ramon?
The first fall frost (32°F) usually arrives around December 22. There’s a 10% chance of a freeze by November 23 and a 90% chance by February 11.
Can it frost in San Ramon after the last frost date?
Yes. Frost can form on clear, calm nights even when the air stays above 32°F. Temperatures of 36°F or lower, cold enough for frost on exposed plants, have a 50% chance of occurring after April 19.
What growing zone is San Ramon?
San Ramon is in USDA Plant Hardiness Zone 9b (average annual extreme minimum temperature 25 to 30°F), based on the 2023 USDA map for ZIP code 94582. See growing zones in California.
More: all California frost dates · California growing zones · UV index today in San Ramon · frost vs. freeze