USDA Hardiness Zone 9b
Frost Dates for 95020 — Gilroy, California
NOAA 1991–2020 normals from Gilroy, CA (194 ft), 1 miles south.
Updated
In Gilroy, the last spring frost (32°F) is around February 24 in half of years and has passed by April 4 in nine years out of ten. The first fall frost comes around November 27, as early as November 10 one year in ten, leaving a typical freeze-free season of 277 days (NOAA, Gilroy, CA).
- Last spring frost
- February 24
- First fall frost
- November 27
- Growing season
- 277 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 Gilroy
Half of springs at Gilroy, CA see their last 32°F night by February 24; only one in ten is past it by January 23, and one in ten still has one after April 4. Planting tender crops after March 8 leaves a 30% risk of a frost on them, after March 21 20%, and after April 4 10%. The 39 days between the even-odds date and the one-in-ten date is wider than at 85% 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 27 in half of years, as early as November 10 one year in ten, and holds off past December 18 one year in ten. A hard freeze of 28°F follows 15 days later, around December 12; in spring the one-in-ten date for 28°F is February 19, 44 days before the 32°F one. The freeze-free season lasts 277 days in a typical year, shorter than at 50% of the 219 California stations; it reaches 317 days one year in ten and falls short of 228 one year in ten. On average 16 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 39 days longer, to about April 4, and return around November 10. A 24°F night is unusual: 49% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Mar 4 | Mar 13 | Mar 23 | Mar 30 | Apr 4 | Apr 10 | Apr 15 | Apr 21 | May 1 |
| 32°F | Jan 23 | Feb 1 | Feb 11 | Feb 17 | Feb 24 | Mar 1 | Mar 8 | Mar 21 | Apr 4 |
| 28°F91% of yrs | Dec 22 | Dec 30 | Jan 4 | Jan 9 | Jan 16 | Jan 23 | Jan 31 | Feb 5 | Feb 19 |
| 24°F49% of yrs | too rare for a date | ||||||||
| 20°F12% of yrs | too rare for a date | ||||||||
| 16°F2% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 20 | Oct 30 | Nov 3 | Nov 6 | Nov 10 | Nov 13 | Nov 17 | Nov 22 | Nov 29 |
| 32°F | Nov 10 | Nov 16 | Nov 20 | Nov 23 | Nov 27 | Dec 1 | Dec 4 | Dec 9 | Dec 18 |
| 28°F91% of yrs | Nov 24 | Dec 1 | Dec 5 | Dec 9 | Dec 12 | Dec 18 | Dec 24 | Jan 1 | Jan 14 |
| 24°F49% of yrs | too rare for a date | ||||||||
| 20°F12% of yrs | too rare for a date | ||||||||
| 16°F2% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Gilroy, 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 95020 →Compare Gilroy with another place →
Weather by month in Gilroy
August is the warmest month at Gilroy, CA, averaging 87°F by day and 54°F at night; December is the coldest at 60°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 69% of years and March still brings one in 32% of years and April still brings one in 12% of years.
Warmth for growing adds up to 3,961 growing degree days a year (base 50°F), fewer than at 61% of the 283 California stations. 38% of them (1,495) have built up by the end of June, and August adds the most, 645. Precipitation totals 19.9 inches a year, most in January (4.6") 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 | 61 | 38 | 4.6 | 89% | 5 | 49 |
| Feb | 64 | 40 | 4.3 | 69% | 2 | 93 |
| Mar | 68 | 43 | 2.6 | 32% | 1 | 179 |
| Apr | 72 | 45 | 1.3 | 12% | <1 | 250 |
| May | 77 | 49 | 0.6 | 1% | 0 | 408 |
| Jun | 83 | 52 | 0.2 | 0% | 0 | 516 |
| Jul | 87 | 54 | 0.0 | 0% | 0 | 639 |
| Aug | 87 | 54 | 0.0 | 0% | 0 | 645 |
| Sep | 85 | 53 | 0.0 | 2% | 0 | 561 |
| Oct | 79 | 48 | 0.9 | 0% | 0 | 414 |
| Nov | 68 | 42 | 1.7 | 56% | 2 | 166 |
| Dec | 60 | 37 | 3.7 | 90% | 7 | 42 |
Monthly normals 1991–2020 at Gilroy, CA (194 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, Watsonville Wtr Wks, CA, 13 miles southwest of Gilroy, has a last frost 27 days earlier (January 28), a first frost 16 days later (December 13), a season 47 days longer.
When it snows in Gilroy, California
Measurable snow is rare here: only 0 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Gilroy, CA, 1 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 95020
| When | What to do |
|---|---|
| December 16 – December 30 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| December 30 – January 13 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| January 27 – February 10 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| February 24 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by September 4 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by November 13 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 27 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 95020 is 1 mile from Gilroy, CA, which stands at 194 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 95020 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.