Last frost date in Foster City, CA

Average last frost
January 17

The average last frost in Foster City is January 17. By February 16 the chance of another 32°F night drops to 1 in 10. The first fall frost usually arrives about December 12, which leaves 333 frost-free days. An early freeze before November 24 happens one year in ten.

Safe after (10% risk)
Feb 16
Average first frost
Dec 12
Frost-free season
333 days
Hard freeze (28°F) ends
Dec 31
Next 6 nights in Foster City

No frost in the next 6 nights

National Weather Service forecast, updated Oct 22, 12:57 UTC

  1. ThuOct 2257°
  2. FriOct 2355°
  3. SatOct 2456°
  4. SunOct 2556°
  5. MonOct 2655°
  6. TueOct 2755°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost Jan 17First frost Dec 12333 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND333 frost-free days
Frost risk through the year at Redwood City, 6.1 miles from Foster City.

Planting calendar for Foster City

Windows count forward or back from the average frost dates above. Click a crop for dates across California.

Start indoorsPlant outSow outdoorsFall plantingAverage last and first frost
Warm-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
TomatoesFeb 15–Mar 1
PumpkinsFeb 15–Mar 1
SunflowersFeb 15–Mar 8
CucumbersFeb 22–Mar 1
CornFeb 15–Mar 1
Sweet potatoesFeb 15–Mar 1
WatermelonFeb 15–Mar 1
Green beansFeb 15–Mar 8
ZucchiniFeb 15–Mar 1
OkraFeb 15–Mar 1
PeppersFeb 15–Mar 1
BasilFeb 15–Mar 1
Butternut squashFeb 15–Mar 1
CantaloupeFeb 15–Mar 1
EggplantFeb 15–Mar 1
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesDec 20–Jan 3
OnionsDec 6–Dec 27
CarrotsDec 27–Jan 31
LettuceJan 3–Jan 24
BroccoliDec 20–Jan 3
BeetsDec 20–Jan 31
PeasDec 6–Dec 20
CabbageDec 20–Jan 3
RadishesDec 13–Jan 24
Brussels sproutsJan 3–Jan 17
SpinachDec 6–Dec 27
CilantroJan 3–Jan 24
KaleDec 20–Jan 3
Collard greensDec 20–Jan 3
TurnipsDec 20–Jan 3
DillJan 17–Jan 31
CeleryJan 24–Jan 31
CauliflowerJan 3–Jan 17
LeeksJan 3–Jan 17
Swiss chardJan 3–Jan 31
ParsleyJan 3–Jan 24
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsDec 15–Jan 15
GarlicOct 15–Nov 30
Daffodil bulbsOct 15–Nov 30
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesDec 20–Jan 3
AsparagusDec 20–Jan 3

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FDec 20Jan 17Feb 16Nov 24Dec 12Jan 14
Hard freeze, 28°FDec 14Dec 31Jan 22Dec 5Dec 26Jan 15

Read the spring 10% column as the date after which only one year in ten still gets frost. That is the safer date for tomatoes, peppers and basil.

Where these numbers come from

NOAA station Redwood City (USC00047339) sits 6.1 miles from the center of Foster City at 31 feet. Its averages cover 1991 to 2020. Low spots, valleys and open fields can keep getting frost a week or two after the station stops; city centers and lakeshores usually get less of it.

Questions

When is the last frost in Foster City, CA?

The average last frost date in Foster City is January 17, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after February 16.

When is the first frost in Foster City?

The first frost in fall usually comes around December 12. One year in ten it arrives before November 24.

How long is the growing season in Foster City?

About 333 days between the average last and first frost.

When should I plant tomatoes in Foster City?

Plant tomato seedlings outside from February 15 to March 1. Start seeds indoors six to eight weeks earlier.

Nearby in California

All 348 cities in California