Last frost date in Rialto, CA
In Rialto, the last spring frost comes around January 10 in an average year. Wait until February 17 if you want 90% odds of no more frost. The first fall frost usually arrives about January 2, which leaves 365 frost-free days. An early freeze before December 11 happens one year in ten.
- Safe after (10% risk)
- Feb 17
- Average first frost
- Jan 2
- Frost-free season
- 365 days
- Hard freeze (28°F) ends
- rare
No frost in the next 6 nights
National Weather Service forecast, updated Oct 22, 12:57 UTC
- ThuOct 2255°
- FriOct 2355°
- SatOct 2456°
- SunOct 2558°
- MonOct 2658°
- TueOct 2758°
Planting calendar for Rialto
Windows count forward or back from the average frost dates above. Click a crop for dates across California.
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
PotatoesDec 13–Dec 27
OnionsNov 29–Dec 20
CarrotsDec 20–Jan 24
LettuceDec 27–Jan 17
BroccoliDec 13–Dec 27
BeetsDec 13–Jan 24
PeasNov 29–Dec 13
CabbageDec 13–Dec 27
RadishesDec 6–Jan 17
Brussels sproutsDec 27–Jan 10
SpinachNov 29–Dec 20
CilantroDec 27–Jan 17
KaleDec 13–Dec 27
Collard greensDec 13–Dec 27
TurnipsDec 13–Dec 27
DillJan 10–Jan 24
CeleryJan 17–Jan 24
CauliflowerDec 27–Jan 10
LeeksDec 27–Jan 10
Swiss chardDec 27–Jan 24
ParsleyDec 27–Jan 17
Tulip bulbsDec 15–Jan 15
GarlicOct 15–Nov 30
Daffodil bulbsOct 15–Nov 30
StrawberriesDec 13–Dec 27
AsparagusDec 13–Dec 27Frost probabilities
| Threshold | Spring, 90% chance later | Spring, 50% | Spring, 10% | Fall, 10% chance earlier | Fall, 50% | Fall, 90% |
|---|---|---|---|---|---|---|
| Light frost, 32°F | Dec 20 | Jan 10 | Feb 17 | Dec 11 | Jan 2 | Feb 7 |
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 Riverside Citrus Experiment (USC00047473) sits 10.5 miles from the center of Rialto at 986 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 Rialto, CA?
The average last frost date in Rialto is January 10, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after February 17.
When is the first frost in Rialto?
The first frost in fall usually comes around January 2. One year in ten it arrives before December 11.
How long is the growing season in Rialto?
About 365 days between the average last and first frost.
When should I plant tomatoes in Rialto?
Plant tomato seedlings outside from February 15 to March 1. Start seeds indoors six to eight weeks earlier.
Nearby in California
- BloomingtonJan 10
- FontanaJan 4
- San BernardinoJan 27
- ColtonJan 10
- Jurupa ValleyJan 9
- Loma LindaJan 27
- Rancho CucamongaJan 4
- RiversideJan 9
- HighlandJan 27
- RedlandsJan 27
- OntarioJan 4
- EastvaleJan 17