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Will it freeze in Hercules in the next 7 nights?
No overnight lows at or below 32°F are forecast in Hercules during the next 7 nights in the available NWS frost forecast.
Tonight: forecast low 54°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 54°F Above 36°F · Mostly Clear
- Fri, Nov 6 53°F Above 36°F · Mostly Clear
- Sat, Nov 7 54°F Above 36°F · Mostly Clear then Patchy Fog
- Sun, Nov 8 53°F Above 36°F · Partly Cloudy then Patchy Fog
- Mon, Nov 9 53°F Above 36°F · Mostly Clear
- Tue, Nov 10 54°F Above 36°F · Partly Cloudy then Slight Chance Light Rain
- Wed, Nov 11 53°F Above 36°F · 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 Hercules
Most years have no 28°F hard freeze at Vallejo, according to NOAA’s 1991–2020 Climate Normals. Check the short-term forecast above during cold snaps.
| 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 | Jan 19 · Mar 4 · Apr 8 | Nov 21 · Dec 7 · Jan 2 | 279 days |
| 32°F freeze | Dec 23 · Jan 17 · Mar 4 | Dec 4 · Dec 27 · Feb 4 | 346 days |
| 28°F hard freeze | Dec 19 · Jan 5 · Jan 19 | Dec 13 · Jan 2 · Jan 19 | 365 days |
Average high temperature by month
1991–2020 normals at Vallejo
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 Hercules, CA come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Vallejo (station USC00049219, elevation 341 ft), 7.8 mi from Hercules. 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 Hercules
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Pinole, CA | 1.9 mi | rare | rare |
| San Pablo, CA | 5.0 mi | rare | rare |
| Vallejo, CA | 6.2 mi | Jan 17 | Dec 27 |
| Richmond, CA | 6.2 mi | rare | rare |
| El Cerrito, CA | 6.8 mi | rare | rare |
| Benicia, CA | 8.1 mi | Jan 17 | Dec 27 |
| Albany, CA | 9.3 mi | rare | rare |
| Martinez, CA | 9.9 mi | Feb 28 | Nov 22 |
| Berkeley, CA | 11 mi | rare | rare |
| American Canyon, CA | 11 mi | Mar 5 | Nov 21 |
Frequently asked questions
When is the last frost in Hercules?
On average, the last spring frost (32°F) in Hercules is around January 17. In about 1 year in 10 it comes after March 4, and in 9 years in 10 it comes after December 23.
When is the first frost in Hercules?
The first fall frost (32°F) usually arrives around December 27. There’s a 10% chance of a freeze by December 4 and a 90% chance by February 4.
Can it frost in Hercules 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 March 4.
What growing zone is Hercules?
Hercules 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 94547. See growing zones in California.
More: all California frost dates · California growing zones · UV index today in Hercules · frost vs. freeze