USDA Hardiness Zone 9b
Frost Dates for 95004 — Aromas, California
NOAA 1991–2020 normals from Watsonville Wtr Wks, CA (95 ft), 8 miles northwest.
Updated
In Aromas, the last spring frost (32°F) is around January 28 in half of years and has passed by March 3 in nine years out of ten. The first fall frost comes around December 13, as early as November 25 one year in ten, leaving a typical freeze-free season of 324 days (NOAA, Watsonville Wtr Wks, CA).
- Last spring frost
- January 28
- First fall frost
- December 13
- Growing season
- 324 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
- 5%
- Snow per year
- 0"
median, 1991–2020
median, 1991–2020
1 of 20 observed
NOAA normal
Frost risk by date in Aromas
Half of springs at Watsonville Wtr Wks, CA see their last 32°F night by January 28; only one in ten is past it by December 23, and one in ten still has one after March 3. Planting tender crops after February 12 leaves a 30% risk of a frost on them, after February 24 20%, and after March 3 10%. The 34 days between the even-odds date and the one-in-ten date is wider than at 65% 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 13 in half of years, as early as November 25 one year in ten, and holds off past January 15 one year in ten. A hard freeze of 28°F is less common: it came in 38% of winters. The freeze-free season lasts 324 days in a typical year, longer than at 78% of the 219 California stations; it reaches 362 days one year in ten and falls short of 278 one year in ten. On average 8 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 46 days longer, to about March 15, and return around November 26. A 24°F night is unusual: 2% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Feb 4 | Feb 24 | Mar 2 | Mar 9 | Mar 15 | Mar 22 | Mar 30 | Apr 5 | Apr 14 |
| 32°F91% of yrs | Dec 23 | Dec 31 | Jan 11 | Jan 20 | Jan 28 | Feb 3 | Feb 12 | Feb 24 | Mar 3 |
| 28°F38% 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 8 | Nov 15 | Nov 18 | Nov 23 | Nov 26 | Nov 29 | Dec 1 | Dec 5 | Dec 12 |
| 32°F91% of yrs | Nov 25 | Dec 1 | Dec 4 | Dec 8 | Dec 13 | Dec 18 | Dec 24 | Jan 1 | Jan 15 |
| 28°F38% of yrs | too rare for a date | ||||||||
| 24°F2% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Watsonville Wtr Wks, 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 95004 →Compare Aromas with another place →
Weather by month in Aromas
September is the warmest month at Watsonville Wtr Wks, CA, averaging 74°F by day and 53°F at night; December is the coldest at 62°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 33% of years and March still brings one in 11% of years.
Warmth for growing adds up to 2,937 growing degree days a year (base 50°F), fewer than at 85% of the 283 California stations. 39% of them (1,135) have built up by the end of June, and August adds the most, 417. Precipitation totals 22.7 inches a year, most in February (4.5") and least in July (0.0"); May to September bring 4% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 62 | 40 | 4.4 | 59% | 3 | 76 |
| Feb | 63 | 42 | 4.5 | 33% | 1 | 96 |
| Mar | 65 | 43 | 3.6 | 11% | <1 | 148 |
| Apr | 68 | 45 | 1.6 | 0% | <1 | 195 |
| May | 69 | 49 | 0.6 | 0% | 0 | 278 |
| Jun | 71 | 52 | 0.1 | 0% | 0 | 342 |
| Jul | 71 | 54 | 0.0 | 0% | 0 | 391 |
| Aug | 72 | 55 | 0.0 | 0% | 0 | 417 |
| Sep | 74 | 53 | 0.1 | 0% | 0 | 405 |
| Oct | 74 | 49 | 1.0 | 0% | 0 | 347 |
| Nov | 68 | 43 | 2.3 | 16% | 1 | 176 |
| Dec | 62 | 39 | 4.5 | 66% | 3 | 66 |
Monthly normals 1991–2020 at Watsonville Wtr Wks, CA (95 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, Gilroy, CA, 9 miles northeast of Aromas, has a last frost 27 days later (February 24), a first frost 16 days earlier (November 27), a season 47 days shorter.
When it snows in Aromas, California
Measurable snow is rare here: only 1 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Watsonville Wtr Wks, CA, 8.3 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 95004
| When | What to do |
|---|---|
| November 19 – December 3 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| December 3 – December 17 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| December 31 – January 14 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| January 28 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by September 20 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by November 29 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| December 13 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 95004 is 8 miles from Watsonville Wtr Wks, CA, which stands at 95 feet, 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 95076 (Watsonville). The 2023 USDA Plant Hardiness Zone Map lists ZIP 95004 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.