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Will it freeze in Foster City in the next 7 nights?
No overnight lows at or below 32°F are forecast in Foster City during the next 7 nights in the available NWS frost forecast.
Tonight: forecast low 55°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 55°F Above 36°F · Mostly Clear
- Fri, Nov 6 56°F Above 36°F · Mostly Clear
- Sat, Nov 7 57°F Above 36°F · Mostly Clear
- Sun, Nov 8 56°F Above 36°F · Partly Cloudy
- Mon, Nov 9 55°F Above 36°F · Partly Cloudy
- Tue, Nov 10 56°F Above 36°F · Partly Cloudy then Slight Chance Light Rain
- Wed, Nov 11 55°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 Foster City
Most years have no 28°F hard freeze at Redwood City, 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 25 · Feb 25 · Mar 31 | Nov 8 · Nov 25 · Dec 14 | 272 days |
| 32°F freeze | Dec 20 · Jan 17 · Feb 16 | Nov 24 · Dec 12 · Jan 14 | 333 days |
| 28°F hard freeze | Dec 14 · Dec 31 · Jan 22 | Dec 5 · Dec 26 · Jan 15 | 365 days |
Average high temperature by month
1991–2020 normals at Redwood City
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 Foster City, CA come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Redwood City (station USC00047339, elevation 31 ft), 6.2 mi from Foster City. 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 Foster City
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| San Mateo, CA | 3.1 mi | rare | rare |
| Redwood City, CA | 3.7 mi | Jan 17 | Dec 12 |
| Belmont, CA | 4.3 mi | Jan 17 | Dec 12 |
| San Carlos, CA | 4.3 mi | Jan 17 | Dec 12 |
| Hillsborough, CA | 6.2 mi | rare | rare |
| Burlingame, CA | 6.2 mi | rare | rare |
| Atherton, CA | 8.1 mi | Jan 17 | Dec 12 |
| Menlo Park, CA | 8.1 mi | Feb 1 | Dec 7 |
| Millbrae, CA | 8.7 mi | rare | rare |
| Hayward, CA | 9.3 mi | rare | rare |
Frequently asked questions
When is the last frost in Foster City?
On average, the last spring frost (32°F) in Foster City is around January 17. In about 1 year in 10 it comes after February 16, and in 9 years in 10 it comes after December 20.
When is the first frost in Foster City?
The first fall frost (32°F) usually arrives around December 12. There’s a 10% chance of a freeze by November 24 and a 90% chance by January 14.
Can it frost in Foster City 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 February 25.
What growing zone is Foster City?
Foster City is in USDA Plant Hardiness Zone 10a (average annual extreme minimum temperature 30 to 35°F), based on the 2023 USDA map for ZIP code 94404. See growing zones in California.
More: all California frost dates · California growing zones · UV index today in Foster City · frost vs. freeze