USDA Hardiness Zone 9b
Frost Dates for 95327 — Jamestown, California
NOAA 1991–2020 normals from Sonora, CA (1,675 ft), 9 miles northeast.
Updated
In Jamestown, the last spring frost (32°F) is around April 9 in half of years and has passed by April 30 in nine years out of ten. The first fall frost comes around November 9, as early as October 19 one year in ten, leaving a typical freeze-free season of 213 days (NOAA, Sonora, CA).
- Last spring frost
- April 9
- First fall frost
- November 9
- Growing season
- 213 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
- 4%
- Snow per year
- 0"
median, 1991–2020
median, 1991–2020
1 of 24 observed
NOAA normal
Frost risk by date in Jamestown
Half of springs at Sonora, CA see their last 32°F night by April 9; only one in ten is past it by March 15, and one in ten still has one after April 30. Planting tender crops after April 18 leaves a 30% risk of a frost on them, after April 23 20%, and after April 30 10%. The 21 days between the even-odds date and the one-in-ten date is narrower than at 84% 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 9 in half of years, as early as October 19 one year in ten, and holds off past November 27 one year in ten. A hard freeze of 28°F follows 18 days later, around November 27; in spring the one-in-ten date for 28°F is April 8, 22 days before the 32°F one. The freeze-free season lasts 213 days in a typical year, shorter than at 77% of the 219 California stations; it reaches 244 days one year in ten and falls short of 186 one year in ten. On average 66 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 21 days longer, to about April 30, and return around October 25. Nights of 24°F, cold enough to damage hardier plants, come in 89% of winters and 16°F in 6%.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 11 | Apr 18 | Apr 22 | Apr 26 | Apr 30 | May 2 | May 6 | May 11 | May 19 |
| 32°F | Mar 15 | Mar 25 | Apr 1 | Apr 5 | Apr 9 | Apr 13 | Apr 18 | Apr 23 | Apr 30 |
| 28°F | Jan 31 | Feb 12 | Feb 23 | Feb 28 | Mar 4 | Mar 11 | Mar 18 | Mar 29 | Apr 8 |
| 24°F89% of yrs | Dec 23 | Jan 1 | Jan 9 | Jan 20 | Jan 28 | Feb 3 | Feb 9 | Feb 19 | Feb 28 |
| 20°F38% of yrs | too rare for a date | ||||||||
| 16°F6% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 7 | Oct 14 | Oct 17 | Oct 21 | Oct 25 | Oct 29 | Nov 1 | Nov 5 | Nov 12 |
| 32°F | Oct 19 | Oct 27 | Nov 1 | Nov 4 | Nov 9 | Nov 12 | Nov 17 | Nov 21 | Nov 27 |
| 28°F | Nov 7 | Nov 15 | Nov 19 | Nov 23 | Nov 27 | Dec 1 | Dec 5 | Dec 9 | Dec 19 |
| 24°F89% of yrs | Nov 24 | Dec 1 | Dec 6 | Dec 11 | Dec 15 | Dec 22 | Jan 1 | Jan 8 | Jan 27 |
| 20°F38% of yrs | too rare for a date | ||||||||
| 16°F6% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Sonora, 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 95327 →Compare Jamestown with another place →
Weather by month in Jamestown
July is the warmest month at Sonora, CA, averaging 93°F by day and 57°F at night; December is the coldest at 55°F and 32°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 68% of years.
Warmth for growing adds up to 3,560 growing degree days a year (base 50°F), fewer than at 72% of the 283 California stations. 31% of them (1,110) have built up by the end of June, and July adds the most, 769. Precipitation totals 32.6 inches a year, most in January (6.3") and least in July (0.0"); May to September bring 6% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 56 | 33 | 6.3 | 99% | 17 | 9 |
| Feb | 58 | 34 | 5.5 | 98% | 12 | 23 |
| Mar | 62 | 37 | 5.4 | 92% | 7 | 67 |
| Apr | 67 | 40 | 3.0 | 68% | 3 | 136 |
| May | 76 | 46 | 1.5 | 9% | <1 | 333 |
| Jun | 85 | 51 | 0.3 | 0% | 0 | 542 |
| Jul | 93 | 57 | 0.0 | 0% | 0 | 769 |
| Aug | 92 | 56 | 0.1 | 0% | 0 | 735 |
| Sep | 87 | 51 | 0.2 | 0% | 0 | 563 |
| Oct | 76 | 43 | 1.6 | 29% | 1 | 304 |
| Nov | 63 | 36 | 3.2 | 91% | 8 | 72 |
| Dec | 55 | 32 | 5.5 | 100% | 18 | 8 |
Monthly normals 1991–2020 at Sonora, CA (1,675 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, New Melones Dam Hq, CA, 10 miles north of Jamestown and 715 feet lower, has a last frost 48 days earlier (February 20), a first frost 32 days later (December 11), a season 77 days longer.
When it snows in Jamestown, California
Measurable snow is rare here: only 1 of 24 winters from 1991 to 2020 recorded 0.1 inch or more at Sonora, CA, 8.9 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 95327
| When | What to do |
|---|---|
| January 29 – February 12 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 12 – February 26 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 12 – March 26 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 9 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 17 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 26 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 9 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 95327 is 9 miles from Sonora, CA, which stands at 1,675 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 95370 (Sonora). The 2023 USDA Plant Hardiness Zone Map lists ZIP 95327 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.