USDA Hardiness Zone 9b
Frost Dates for 94551 — Livermore, California
NOAA 1991–2020 normals from Livermore, CA (393 ft), 6 miles east.
Updated
In Livermore, the last spring frost (32°F) is around February 15 in half of years and has passed by March 13 in nine years out of ten. The first fall frost comes around December 2, as early as November 16 one year in ten, leaving a typical freeze-free season of 292 days (NOAA, Livermore, CA).
- Last spring frost
- February 15
- First fall frost
- December 2
- Growing season
- 292 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 20 observed
NOAA normal
Frost risk by date in Livermore
Half of springs at Livermore, CA see their last 32°F night by February 15; only one in ten is past it by January 12, and one in ten still has one after March 13. Planting tender crops after February 28 leaves a 30% risk of a frost on them, after March 5 20%, and after March 13 10%. The 26 days between the even-odds date and the one-in-ten date is narrower than at 67% 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 2 in half of years, as early as November 16 one year in ten, and holds off past December 28 one year in ten. A hard freeze of 28°F follows 16 days later, around December 18; in spring the one-in-ten date for 28°F is February 10, 31 days before the 32°F one. The freeze-free season lasts 292 days in a typical year, longer than at 59% of the 219 California stations; it reaches 330 days one year in ten and falls short of 257 one year in ten. On average 13 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 38 days longer, to about March 25, and return around November 18. A 24°F night is unusual: 24% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Feb 26 | Mar 7 | Mar 13 | Mar 18 | Mar 25 | Mar 31 | Apr 3 | Apr 8 | Apr 13 |
| 32°F99% of yrs | Jan 12 | Jan 26 | Feb 1 | Feb 9 | Feb 15 | Feb 22 | Feb 28 | Mar 5 | Mar 13 |
| 28°F76% of yrs | Dec 19 | Dec 26 | Dec 30 | Jan 3 | Jan 10 | Jan 15 | Jan 24 | Jan 31 | Feb 10 |
| 24°F24% of yrs | too rare for a date | ||||||||
| 20°F0% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Nov 4 | Nov 9 | Nov 12 | Nov 14 | Nov 18 | Nov 21 | Nov 24 | Nov 28 | Dec 2 |
| 32°F99% of yrs | Nov 16 | Nov 22 | Nov 25 | Nov 29 | Dec 2 | Dec 5 | Dec 9 | Dec 14 | Dec 28 |
| 28°F76% of yrs | Nov 29 | Dec 4 | Dec 8 | Dec 13 | Dec 18 | Dec 24 | Dec 30 | Jan 6 | Jan 17 |
| 24°F24% of yrs | too rare for a date | ||||||||
| 20°F0% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Livermore, 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 94551 →Compare Livermore with another place →
Weather by month in Livermore
July is the warmest month at Livermore, CA, averaging 89°F by day and 57°F at night; December is the coldest at 57°F and 39°F. From April to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 59% of years and March still brings one in 27% of years.
Warmth for growing adds up to 4,091 growing degree days a year (base 50°F), fewer than at 58% of the 283 California stations. 36% of them (1,484) have built up by the end of June, and July adds the most, 707. Precipitation totals 14.5 inches a year, most in January (2.8") and least in July (0.0"); May to September bring 5% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 57 | 39 | 2.8 | 80% | 5 | 33 |
| Feb | 61 | 41 | 2.7 | 59% | 2 | 70 |
| Mar | 66 | 43 | 2.2 | 27% | <1 | 157 |
| Apr | 71 | 46 | 1.1 | 1% | 0 | 247 |
| May | 77 | 50 | 0.5 | 0% | 0 | 412 |
| Jun | 84 | 54 | 0.1 | 0% | 0 | 566 |
| Jul | 89 | 57 | 0.0 | 0% | 0 | 707 |
| Aug | 89 | 57 | 0.0 | 0% | 0 | 701 |
| Sep | 86 | 55 | 0.1 | 0% | 0 | 609 |
| Oct | 77 | 50 | 0.8 | 0% | 0 | 417 |
| Nov | 65 | 43 | 1.5 | 43% | 1 | 138 |
| Dec | 57 | 39 | 2.7 | 84% | 5 | 35 |
Monthly normals 1991–2020 at Livermore, CA (393 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, Hayward Air Terminal, CA, 11 miles west of Livermore and 350 feet lower, has a 32°F night in 45% of winters against 99% here, and a coolest-month low 4°F warmer (43°F).
When it snows in Livermore, California
Measurable snow is rare here: only 0 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Livermore, CA, 5.9 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 94551
| When | What to do |
|---|---|
| December 7 – December 21 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| December 21 – January 4 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| January 18 – February 1 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| February 15 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by September 9 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by November 18 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| December 2 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 94551 is 6 miles from Livermore, CA, which stands at 393 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station; its figures are presented in full for 94568 (Dublin). The 2023 USDA Plant Hardiness Zone Map lists ZIP 94551 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.