USDA Hardiness Zone 9b
Frost Dates for 94591 — Vallejo, California
NOAA 1991–2020 normals from Vallejo, CA (341 ft), 1 miles east.
Updated
A freeze (32°F) reaches Vallejo in 75% of winters. When it does, the first fall frost comes around December 27 and the last spring frost around January 17; after March 4 the chance of another is under 7%.
- Last spring frost
- January 17
- First fall frost
- December 27
- Winters with a freeze
- 75%
- Hardiness zone
- 9b
50%, in freezing years
50%, in freezing years
32°F or below, 1991–2020
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 Vallejo
In the 75% of winters that bring a 32°F night, half of springs at Vallejo, CA see their last 32°F night by January 17; only one in ten is past it by December 23, and one in ten still has one after March 4. Counting the winters with no freeze at all, the risk of a 32°F night after March 4 is under 7% and after January 17 37%. The 46 days between the even-odds date and the one-in-ten date is wider than at 95% 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 27 in half of years, as early as December 4 one year in ten, and holds off past February 4 one year in ten. A hard freeze of 28°F is less common: it came in 23% of winters. The freeze-free season lasts 346 days in a typical year, longer than at 91% of the 219 California stations; it reaches 365 days one year in ten and falls short of 291 one year in ten. On average 5 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 4, and return around December 7. A 24°F night is unusual: 4% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jan 19 | Feb 1 | Feb 15 | Feb 27 | Mar 4 | Mar 13 | Mar 20 | Mar 29 | Apr 8 |
| 32°F75% of yrs | Dec 23 | Dec 31 | Jan 5 | Jan 11 | Jan 17 | Jan 25 | Feb 2 | Feb 18 | Mar 4 |
| 28°F23% of yrs | too rare for a date | ||||||||
| 24°F4% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Nov 21 | Nov 27 | Dec 1 | Dec 3 | Dec 7 | Dec 11 | Dec 14 | Dec 21 | Jan 2 |
| 32°F75% of yrs | Dec 4 | Dec 11 | Dec 17 | Dec 21 | Dec 27 | Jan 1 | Jan 7 | Jan 16 | Feb 4 |
| 28°F23% of yrs | too rare for a date | ||||||||
| 24°F4% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Vallejo, 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 94591 →Compare Vallejo with another place →
Compared with the next station
The nearest other station, Martinez Wtp, CA, 8 miles southeast of Vallejo and 301 feet lower, has a last frost 42 days later (February 28), a first frost 35 days earlier (November 22), a season 80 days shorter.
When it snows in Vallejo, California
Measurable snow is rare here: only 0 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Martinez Wtp, CA, 7.9 miles away, so there is no typical first-snow date to plan around.
Where these figures come from
ZIP 94591 is 1 mile from Vallejo, CA, which stands at 341 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 94591 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.