USDA Hardiness Zone 9a
Frost Dates for 93280 — Wasco, California
NOAA 1991–2020 normals from Wasco, CA (291 ft), 2 miles southeast.
Updated
In Wasco, the last spring frost (32°F) is around January 31 in half of years and has passed by February 27 in nine years out of ten. The first fall frost comes around December 5, as early as November 21 one year in ten, leaving a typical freeze-free season of 315 days (NOAA, Wasco, CA).
- Last spring frost
- January 31
- First fall frost
- December 5
- Growing season
- 315 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
- 5%
- Snow per year
- 0.2"
median, 1991–2020
median, 1991–2020
1 of 20 observed
NOAA normal
Frost risk by date in Wasco
Half of springs at Wasco, CA see their last 32°F night by January 31; only one in ten is past it by January 2, and one in ten still has one after February 27. Planting tender crops after February 11 leaves a 30% risk of a frost on them, after February 16 20%, and after February 27 10%. The 27 days between the even-odds date and the one-in-ten date is narrower 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 5 in half of years, as early as November 21 one year in ten, and holds off past January 2 one year in ten. A hard freeze of 28°F follows 11 days later, around December 16; in spring the one-in-ten date for 28°F is February 4, 23 days before the 32°F one. The freeze-free season lasts 315 days in a typical year, longer than at 72% of the 219 California stations; it reaches 344 days one year in ten and falls short of 278 one year in ten. On average 25 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 26 days longer, to about February 26, and return around November 24. A 24°F night is unusual: 17% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jan 30 | Feb 8 | Feb 15 | Feb 22 | Feb 26 | Mar 1 | Mar 7 | Mar 14 | Mar 25 |
| 32°F97% of yrs | Jan 2 | Jan 10 | Jan 18 | Jan 25 | Jan 31 | Feb 5 | Feb 11 | Feb 16 | Feb 27 |
| 28°F65% of yrs | Dec 8 | Dec 19 | Dec 28 | Dec 31 | Jan 4 | Jan 10 | Jan 17 | Jan 27 | Feb 4 |
| 24°F17% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Nov 9 | Nov 15 | Nov 18 | Nov 21 | Nov 24 | Nov 27 | Nov 30 | Dec 4 | Dec 10 |
| 32°F97% of yrs | Nov 21 | Nov 26 | Nov 29 | Dec 1 | Dec 5 | Dec 9 | Dec 13 | Dec 22 | Jan 2 |
| 28°F65% of yrs | Nov 29 | Dec 3 | Dec 8 | Dec 12 | Dec 16 | Dec 23 | Dec 29 | Jan 3 | Jan 16 |
| 24°F17% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Wasco, 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 93280 →Compare Wasco with another place →
Weather by month in Wasco
July is the warmest month at Wasco, CA, averaging 100°F by day and 69°F at night; December is the coldest at 59°F and 38°F. From March to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 45% of years.
Warmth for growing adds up to 6,093 growing degree days a year (base 50°F), more than at 93% of the 283 California stations. 39% of them (2,393) have built up by the end of June, and July adds the most, 1,066. Precipitation totals 7.1 inches a year, most in March (1.4") 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 | 59 | 39 | 1.3 | 77% | 8 | 54 |
| Feb | 65 | 42 | 1.2 | 45% | 3 | 122 |
| Mar | 71 | 46 | 1.4 | 6% | <1 | 276 |
| Apr | 77 | 50 | 0.6 | 0% | <1 | 412 |
| May | 86 | 57 | 0.3 | 0% | 0 | 671 |
| Jun | 94 | 63 | 0.1 | 0% | 0 | 858 |
| Jul | 100 | 69 | 0.0 | 0% | 0 | 1066 |
| Aug | 99 | 66 | 0.0 | 0% | 0 | 1011 |
| Sep | 94 | 62 | 0.0 | 0% | 0 | 829 |
| Oct | 82 | 53 | 0.5 | 0% | 0 | 550 |
| Nov | 69 | 44 | 0.6 | 33% | 3 | 200 |
| Dec | 59 | 38 | 1.1 | 80% | 11 | 43 |
Monthly normals 1991–2020 at Wasco, CA (291 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, Delano, CA, 13 miles northeast of Wasco, has the same 50% last-frost date, a first frost 3 days later (December 8), a season 6 days shorter.
When it snows in Wasco, California
Measurable snow is rare here: only 1 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Wasco, CA, 1.6 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 93280
| When | What to do |
|---|---|
| November 22 – December 6 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| December 6 – December 20 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| January 3 – January 17 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| January 31 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by September 12 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by November 21 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| December 5 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 93280 is 2 miles from Wasco, CA, which stands at 291 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 93280 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.