USDA Hardiness Zone 9b
Frost Dates for 92233 — Calipatria, California
NOAA 1991–2020 normals from Brawley 2 SW, CA, 13 miles south.
Updated
In Calipatria, the last spring frost (32°F) is around January 16 in half of years and has passed by February 17 in nine years out of ten. The first fall frost comes around December 19, as early as December 2 one year in ten, leaving a typical freeze-free season of 335 days (NOAA, Brawley 2 SW, CA).
- Last spring frost
- January 16
- First fall frost
- December 19
- Growing season
- 335 days
- Hardiness zone
- 9b
50% probability
50% probability
freeze-free, 50%
25 to 30°F (-3.9 to -1.1°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 0%
- Snow per year
- 0"
median, 1991–2020
median, 1991–2020
0 of 17 observed
NOAA normal
Frost risk by date in Calipatria
Half of springs at Brawley 2 SW, CA see their last 32°F night by January 16; only one in ten is past it by December 21, and one in ten still has one after February 17. Planting tender crops after February 1 leaves a 30% risk of a frost on them, after February 7 20%, and after February 17 10%. The 32 days between the even-odds date and the one-in-ten date is wider than at 55% of the 220 California stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.
In fall the first 32°F night comes by December 19 in half of years, as early as December 2 one year in ten, and holds off past January 17 one year in ten. A hard freeze of 28°F is less common: it came in 34% of winters. The freeze-free season lasts 335 days in a typical year, longer than at 86% of the 219 California stations; it reaches 363 days one year in ten and falls short of 305 one year in ten. On average 6 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 25 days longer, to about February 10, and return around December 6. A 24°F night is unusual: 2% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jan 13 | Jan 22 | Jan 31 | Feb 4 | Feb 10 | Feb 14 | Feb 19 | Feb 24 | Feb 28 |
| 32°F91% of yrs | Dec 21 | Dec 31 | Jan 5 | Jan 10 | Jan 16 | Jan 24 | Feb 1 | Feb 7 | Feb 17 |
| 28°F34% of yrs | too rare for a date | ||||||||
| 24°F2% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Nov 22 | Nov 27 | Dec 1 | Dec 4 | Dec 6 | Dec 9 | Dec 13 | Dec 16 | Dec 21 |
| 32°F91% of yrs | Dec 2 | Dec 7 | Dec 11 | Dec 15 | Dec 19 | Dec 23 | Dec 28 | Jan 3 | Jan 17 |
| 28°F34% of yrs | too rare for a date | ||||||||
| 24°F2% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Brawley 2 SW, CA, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 92233 →Compare Calipatria with another place →
Weather by month in Calipatria
August is the warmest month at Brawley 2 SW, CA, averaging 108°F by day and 78°F at night; December is the coldest at 70°F and 41°F. From March to November the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 27% of years.
Warmth for growing adds up to 8,739 growing degree days a year (base 50°F), more than at 98% of the 283 California stations. 40% of them (3,529) have built up by the end of June, and August adds the most, 1,336. Precipitation totals 2.4 inches a year, most in January (0.5") and least in May (0.0"); May to September bring 8% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 72 | 41 | 0.5 | 61% | 2 | 209 |
| Feb | 75 | 45 | 0.5 | 27% | <1 | 271 |
| Mar | 81 | 50 | 0.3 | 1% | <1 | 481 |
| Apr | 87 | 54 | 0.1 | 0% | 0 | 623 |
| May | 95 | 61 | 0.0 | 0% | 0 | 860 |
| Jun | 104 | 68 | 0.0 | 0% | 0 | 1086 |
| Jul | 108 | 77 | 0.0 | 0% | 0 | 1314 |
| Aug | 108 | 78 | 0.1 | 0% | 0 | 1336 |
| Sep | 104 | 71 | 0.1 | 0% | 0 | 1127 |
| Oct | 93 | 60 | 0.1 | 0% | 0 | 825 |
| Nov | 80 | 49 | 0.2 | 7% | 1 | 435 |
| Dec | 70 | 41 | 0.5 | 67% | 3 | 174 |
Monthly normals 1991–2020 at Brawley 2 SW, CA, NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, Imperial, CA, 20 miles south of Calipatria, has a last frost 12 days earlier (January 4), a first frost 7 days later (December 26), a season 25 days longer.
When it snows in Calipatria, California
Measurable snow is rare here: only 0 of 17 winters from 1991 to 2020 recorded 0.1 inch or more at Brawley 2 SW, CA, 12.5 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 92233
| When | What to do |
|---|---|
| November 7 – November 21 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| November 21 – December 5 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| December 19 – January 2 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| January 16 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by September 26 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by December 5 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| December 19 onward | Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter. |
The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.
Where these figures come from
ZIP 92233 is 13 miles from Brawley 2 SW, CA, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 92227 (Brawley). The 2023 USDA Plant Hardiness Zone Map lists ZIP 92233 in zone 9b, the band where the coldest night of the year averaged 25 to 30°F (-3.9 to -1.1°C) over 1991–2020; a zone describes winter lows, not frost dates.
Frost dates across California →
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.