USDA Hardiness Zone 9a
Frost Dates for 93660 — San Joaquin, California
NOAA 1991–2020 normals from Five Points 5 SSW, CA (285 ft), 16 miles south.
Updated
In San Joaquin, the last spring frost (32°F) is around February 27 in half of years and has passed by April 13 in nine years out of ten. The first fall frost comes around November 26, as early as November 8 one year in ten, leaving a typical freeze-free season of 271 days (NOAA, Five Points 5 SSW, CA).
- Last spring frost
- February 27
- First fall frost
- November 26
- Growing season
- 271 days
- Hardiness zone
- 9a
50% probability
50% probability
freeze-free, 50%
20 to 25°F (-6.7 to -3.9°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 0%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
0 of 16 observed
NOAA normal
Frost risk by date in San Joaquin
Half of springs at Five Points 5 SSW, CA see their last 32°F night by February 27; only one in ten is past it by January 21, and one in ten still has one after April 13. Planting tender crops after March 18 leaves a 30% risk of a frost on them, after March 31 20%, and after April 13 10%. The 45 days between the even-odds date and the one-in-ten date is wider than at 93% 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 November 26 in half of years, as early as November 8 one year in ten, and holds off past December 16 one year in ten. A hard freeze of 28°F follows 13 days later, around December 9; in spring the one-in-ten date for 28°F is March 12, 32 days before the 32°F one. The freeze-free season lasts 271 days in a typical year, shorter than at 55% of the 219 California stations; it reaches 313 days one year in ten and falls short of 219 one year in ten. On average 23 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 35 days longer, to about April 3, and return around November 12. A 24°F night is unusual: 48% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Feb 27 | Mar 9 | Mar 19 | Mar 28 | Apr 3 | Apr 8 | Apr 14 | Apr 21 | May 13 |
| 32°F | Jan 21 | Feb 1 | Feb 11 | Feb 21 | Feb 27 | Mar 5 | Mar 18 | Mar 31 | Apr 13 |
| 28°F89% of yrs | Dec 20 | Dec 30 | Jan 5 | Jan 13 | Jan 21 | Jan 28 | Feb 3 | Feb 19 | Mar 12 |
| 24°F48% of yrs | too rare for a date | ||||||||
| 20°F14% of yrs | too rare for a date | ||||||||
| 16°F1% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 26 | Nov 1 | Nov 5 | Nov 8 | Nov 12 | Nov 15 | Nov 18 | Nov 21 | Nov 26 |
| 32°F | Nov 8 | Nov 16 | Nov 19 | Nov 23 | Nov 26 | Nov 30 | Dec 3 | Dec 7 | Dec 16 |
| 28°F89% of yrs | Nov 23 | Nov 29 | Dec 1 | Dec 5 | Dec 9 | Dec 13 | Dec 19 | Dec 31 | Jan 12 |
| 24°F48% of yrs | too rare for a date | ||||||||
| 20°F14% of yrs | too rare for a date | ||||||||
| 16°F1% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Five Points 5 SSW, 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 93660 →Compare San Joaquin with another place →
Weather by month in San Joaquin
July is the warmest month at Five Points 5 SSW, CA, averaging 99°F by day and 63°F at night; December is the coldest at 59°F and 37°F. From May to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 66% of years and March still brings one in 34% of years and April still brings one in 15% of years.
Warmth for growing adds up to 5,527 growing degree days a year (base 50°F), more than at 80% of the 283 California stations. 39% of them (2,132) have built up by the end of June, and July adds the most, 963.
| Month | High °F | Low °F | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|
| Jan | 59 | 38 | 84% | 7 | 39 |
| Feb | 65 | 40 | 66% | 2 | 97 |
| Mar | 71 | 44 | 34% | 1 | 239 |
| Apr | 77 | 47 | 15% | <1 | 363 |
| May | 86 | 54 | 0% | <1 | 615 |
| Jun | 94 | 58 | 4% | <1 | 779 |
| Jul | 99 | 63 | 1% | <1 | 963 |
| Aug | 98 | 62 | 0% | 0 | 927 |
| Sep | 94 | 58 | 0% | 0 | 778 |
| Oct | 82 | 50 | 3% | 0 | 500 |
| Nov | 69 | 41 | 60% | 3 | 180 |
| Dec | 59 | 37 | 90% | 10 | 47 |
Monthly normals 1991–2020 at Five Points 5 SSW, CA (285 ft), 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, Lemoore Reeves NAS, CA, 22 miles southeast of San Joaquin, has a last frost 3 days earlier (February 24), a first frost 4 days earlier (November 22), a season 6 days shorter.
When it snows in San Joaquin, California
Measurable snow is rare here: only 0 of 16 winters from 1991 to 2020 recorded 0.1 inch or more at Five Points 5 SSW, CA, 16.3 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 93660
| When | What to do |
|---|---|
| December 19 – January 2 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| January 2 – January 16 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| January 30 – February 13 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| February 27 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by September 3 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by November 12 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 26 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 93660 is 16 miles from Five Points 5 SSW, CA, which stands at 285 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 93660 in zone 9a, the band where the coldest night of the year averaged 20 to 25°F (-6.7 to -3.9°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.