Last frost date in South San Francisco, CA

Average last frost
December 29

Expect the last frost in South San Francisco around December 29. Frost after January 13 happens in only one year out of ten. The first fall frost usually arrives about December 26, which leaves 365 frost-free days. An early freeze before December 11 happens one year in ten.

Safe after (10% risk)
Jan 13
Average first frost
Dec 26
Frost-free season
365 days
Hard freeze (28°F) ends
rare
Next 6 nights in South San Francisco

No frost in the next 6 nights

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

  1. ThuOct 2254°
  2. FriOct 2350°
  3. SatOct 2452°
  4. SunOct 2556°
  5. MonOct 2656°
  6. TueOct 2756°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost Dec 29First frost Dec 26365 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND365 frost-free days
Frost risk through the year at San Francisco International Airport, 2.5 miles from South San Francisco.

Planting calendar for South San Francisco

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
TomatoesJan 5–Jan 19
PumpkinsJan 12–Jan 26
SunflowersDec 29–Jan 19
CucumbersJan 12–Jan 19
CornJan 5–Jan 19
Sweet potatoesJan 19–Feb 2
WatermelonJan 12–Jan 26
Green beansJan 5–Jan 26
ZucchiniJan 5–Jan 19
OkraJan 19–Feb 2
PeppersJan 12–Jan 26
BasilJan 5–Jan 19
Butternut squashJan 5–Jan 19
CantaloupeJan 12–Jan 26
EggplantJan 12–Jan 26
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesDec 1–Dec 15
OnionsNov 17–Dec 8
CarrotsDec 8–Jan 12
LettuceDec 15–Jan 5
BroccoliDec 1–Dec 15
BeetsDec 1–Jan 12
PeasNov 17–Dec 1
CabbageDec 1–Dec 15
RadishesNov 24–Jan 5
Brussels sproutsDec 15–Dec 29
SpinachNov 17–Dec 8
CilantroDec 15–Jan 5
KaleDec 1–Dec 15
Collard greensDec 1–Dec 15
TurnipsDec 1–Dec 15
DillDec 29–Jan 12
CeleryJan 5–Jan 12
CauliflowerDec 15–Dec 29
LeeksDec 15–Dec 29
Swiss chardDec 15–Jan 12
ParsleyDec 15–Jan 5
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsDec 15–Jan 15
GarlicOct 15–Nov 30
Daffodil bulbsOct 15–Nov 30
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesDec 1–Dec 15
AsparagusDec 1–Dec 15

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FDec 11Dec 29Jan 13Dec 11Dec 26Jan 13

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 San Francisco International Airport (USW00023234) sits 2.5 miles from the center of South San Francisco at 8 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 South San Francisco, CA?

The average last frost date in South San Francisco is December 29, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after January 13.

When is the first frost in South San Francisco?

The first frost in fall usually comes around December 26. One year in ten it arrives before December 11.

How long is the growing season in South San Francisco?

About 365 days between the average last and first frost.

When should I plant tomatoes in South San Francisco?

Plant tomato seedlings outside from January 5 to January 19. Start seeds indoors six to eight weeks earlier.

Nearby in California

All 348 cities in California