USDA Hardiness Zone 9b
Frost Dates for 95932 — Colusa, California
NOAA 1991–2020 normals from Colusa 2 SSW, CA (50 ft), 5 miles south.
Updated
In Colusa, the last spring frost (32°F) is around February 14 in half of years and has passed by March 31 in nine years out of ten. The first fall frost comes around December 1, as early as November 11 one year in ten, leaving a typical freeze-free season of 293 days (NOAA, Colusa 2 SSW, CA).
- Last spring frost
- February 14
- First fall frost
- December 1
- Growing season
- 293 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 24 observed
NOAA normal
Frost risk by date in Colusa
Half of springs at Colusa 2 SSW, CA see their last 32°F night by February 14; only one in ten is past it by January 2, and one in ten still has one after March 31. Planting tender crops after February 28 leaves a 30% risk of a frost on them, after March 13 20%, and after March 31 10%. The 45 days between the even-odds date and the one-in-ten date is wider than at 93% 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 1 in half of years, as early as November 11 one year in ten, and holds off past December 26 one year in ten. A hard freeze of 28°F follows 14 days later, around December 15; in spring the one-in-ten date for 28°F is February 20, 39 days before the 32°F one. The freeze-free season lasts 293 days in a typical year, longer than at 60% of the 219 California stations; it reaches 334 days one year in ten and falls short of 240 one year in ten. On average 17 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 45 days longer, to about March 31, and return around November 12. A 24°F night is unusual: 21% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Feb 21 | Mar 4 | Mar 14 | Mar 24 | Mar 31 | Apr 5 | Apr 9 | Apr 15 | Apr 22 |
| 32°F98% of yrs | Jan 2 | Jan 16 | Jan 27 | Feb 5 | Feb 14 | Feb 22 | Feb 28 | Mar 13 | Mar 31 |
| 28°F75% of yrs | Dec 11 | Dec 21 | Dec 29 | Jan 2 | Jan 8 | Jan 14 | Jan 22 | Feb 5 | Feb 20 |
| 24°F21% of yrs | too rare for a date | ||||||||
| 20°F2% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 28 | Nov 2 | Nov 5 | Nov 9 | Nov 12 | Nov 16 | Nov 20 | Nov 24 | Nov 30 |
| 32°F98% of yrs | Nov 11 | Nov 17 | Nov 23 | Nov 27 | Dec 1 | Dec 4 | Dec 8 | Dec 13 | Dec 26 |
| 28°F75% of yrs | Nov 24 | Dec 1 | Dec 6 | Dec 10 | Dec 15 | Dec 19 | Dec 28 | Jan 2 | Jan 17 |
| 24°F21% of yrs | too rare for a date | ||||||||
| 20°F2% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Colusa 2 SSW, 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 95932 →Compare Colusa with another place →
Weather by month in Colusa
July is the warmest month at Colusa 2 SSW, CA, averaging 92°F by day and 60°F at night; December is the coldest at 55°F and 38°F. From April to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 47% of years and March still brings one in 22% of years.
Warmth for growing adds up to 4,582 growing degree days a year (base 50°F), more than at 50% of the 283 California stations. 39% of them (1,792) have built up by the end of June, and July adds the most, 811. Precipitation totals 17.2 inches a year, most in January (3.6") and least in July (0.0"); May to September bring 8% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 55 | 38 | 3.6 | 77% | 5 | 16 |
| Feb | 60 | 41 | 3.0 | 47% | 2 | 65 |
| Mar | 67 | 44 | 2.2 | 22% | 1 | 177 |
| Apr | 73 | 46 | 1.0 | 10% | <1 | 296 |
| May | 81 | 53 | 0.8 | 0% | <1 | 535 |
| Jun | 88 | 59 | 0.5 | 0% | 0 | 704 |
| Jul | 92 | 60 | 0.0 | 0% | 0 | 811 |
| Aug | 92 | 58 | 0.0 | 0% | 0 | 772 |
| Sep | 89 | 54 | 0.1 | 0% | 0 | 653 |
| Oct | 79 | 48 | 0.9 | 1% | 0 | 418 |
| Nov | 64 | 42 | 1.9 | 48% | 2 | 121 |
| Dec | 55 | 38 | 3.2 | 82% | 7 | 17 |
Monthly normals 1991–2020 at Colusa 2 SSW, CA (50 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, Willows 6 W, CA, 23 miles northwest of Colusa and 184 feet higher, has a last frost 7 days later (February 21), a first frost 5 days later (December 6), a season 4 days shorter.
When it snows in Colusa, California
Measurable snow is rare here: only 0 of 24 winters from 1991 to 2020 recorded 0.1 inch or more at Colusa 2 SSW, CA, 4.8 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 95932
| When | What to do |
|---|---|
| December 6 – December 20 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| December 20 – January 3 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| January 17 – January 31 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| February 14 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by September 8 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by November 17 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| December 1 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 95932 is 5 miles from Colusa 2 SSW, CA, which stands at 50 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 95932 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.