Last frost date in San Ramon, CA

Average last frost
March 8

The average last frost in San Ramon is March 8. By April 15 the chance of another 32°F night drops to 1 in 10. The first fall frost usually arrives about December 22, which leaves 282 frost-free days. An early freeze before November 23 happens one year in ten.

Safe after (10% risk)
Apr 15
Average first frost
Dec 22
Frost-free season
282 days
Hard freeze (28°F) ends
Feb 8
Next 6 nights in San Ramon

No frost in the next 6 nights

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

  1. ThuOct 2250°
  2. FriOct 2345°
  3. SatOct 2448°
  4. SunOct 2549°
  5. MonOct 2648°
  6. TueOct 2749°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost Mar 8First frost Dec 22282 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND282 frost-free days
Frost risk through the year at Mount Diablo Junction, 7.9 miles from San Ramon.

Planting calendar for San Ramon

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
TomatoesMar 15–Mar 29
PumpkinsMar 22–Apr 5
SunflowersMar 8–Mar 29
CucumbersMar 22–Mar 29
CornMar 15–Mar 29
Sweet potatoesMar 29–Apr 12
WatermelonMar 22–Apr 5
Green beansMar 15–Apr 5
ZucchiniMar 15–Mar 29
OkraMar 29–Apr 12
PeppersMar 22–Apr 5
BasilMar 15–Mar 29
Butternut squashMar 15–Mar 29
CantaloupeMar 22–Apr 5
EggplantMar 22–Apr 5
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesFeb 8–Feb 22
OnionsJan 25–Feb 15
CarrotsFeb 15–Mar 22
LettuceFeb 22–Mar 15
BroccoliFeb 8–Feb 22
BeetsFeb 8–Mar 22
PeasJan 25–Feb 8
CabbageFeb 8–Feb 22
RadishesFeb 1–Mar 15
Brussels sproutsFeb 22–Mar 8
SpinachJan 25–Feb 15
CilantroFeb 22–Mar 15
KaleFeb 8–Feb 22
Collard greensFeb 8–Feb 22
TurnipsFeb 8–Feb 22
DillMar 8–Mar 22
CeleryMar 15–Mar 22
CauliflowerFeb 22–Mar 8
LeeksFeb 22–Mar 8
Swiss chardFeb 22–Mar 22
ParsleyFeb 22–Mar 15
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsDec 15–Jan 15
GarlicOct 15–Nov 30
Daffodil bulbsOct 15–Nov 30
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesFeb 8–Feb 22
AsparagusFeb 8–Feb 22

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FJan 12Mar 8Apr 15Nov 23Dec 22Feb 11
Hard freeze, 28°FDec 21Feb 8Mar 23Dec 8Jan 16Mar 3

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 Mount Diablo Junction (USC00045915) sits 7.9 miles from the center of San Ramon at 2,170 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 San Ramon, CA?

The average last frost date in San Ramon is March 8, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after April 15.

When is the first frost in San Ramon?

The first frost in fall usually comes around December 22. One year in ten it arrives before November 23.

How long is the growing season in San Ramon?

About 282 days between the average last and first frost.

When should I plant tomatoes in San Ramon?

Plant tomato seedlings outside from March 15 to March 29. Start seeds indoors six to eight weeks earlier.

Nearby in California

All 348 cities in California