USDA Hardiness Zone 10a
Frost Dates for 92128 — San Diego, California
NOAA 1991–2020 normals from Rancho Bernardo, CA (690 ft), 2 miles north.
Updated
Frost is not a yearly event in San Diego: a night at or below 32°F came in 21% of the winters of 1991–2020 at Rancho Bernardo, CA, and a 36°F night, cold enough for frost on exposed leaves, in 83%. There is no reliable "last frost date" here; most years have none.
- Winters with a freeze
- 21%
- Winters with 36°F
- 83%
- Coldest month low
- —
- Hardiness zone
- 10a
32°F or below, 1991–2020
frost possible on leaves
30 to 35°F (-1.1 to 1.7°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 19 observed
NOAA normal
Frost risk by date in San Diego
At Rancho Bernardo, CA, 2 miles north of San Diego, 21% of the winters of 1991–2020 had at least one night at or below 32°F, 1% reached 28°F. Nights of 36°F, enough for frost on exposed leaves, are more common (83% of winters) and, when they come, fall between about December 23 and January 23. 62 of the 283 other California stations behind this site's ZIP pages freeze in fewer than half of winters too.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F83% of yrs | Dec 17 | Dec 29 | Jan 6 | Jan 13 | Jan 23 | Jan 31 | Feb 8 | Feb 19 | Feb 28 |
| 32°F21% of yrs | too rare for a date | ||||||||
| 28°F1% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F83% of yrs | Dec 1 | Dec 8 | Dec 13 | Dec 18 | Dec 23 | Dec 28 | Jan 2 | Jan 10 | Jan 31 |
| 32°F21% of yrs | too rare for a date | ||||||||
| 28°F1% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Rancho Bernardo, 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 92128 →Compare San Diego with another place →
Compared with the next station
The nearest other station, Escondido #2, CA, 9 miles north of San Diego, has a 32°F night in 39% of winters against 21% here.
When it snows in San Diego, California
Measurable snow is rare here: only 0 of 19 winters from 1991 to 2020 recorded 0.1 inch or more at Poway Valley, CA, 2.7 miles away, so there is no typical first-snow date to plan around.
Where these figures come from
ZIP 92128 is 2 miles from Rancho Bernardo, CA, which stands at 690 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 4 other ZIP codes share the station; its figures are presented in full for 92129 (San Diego). The 2023 USDA Plant Hardiness Zone Map lists ZIP 92128 in zone 10a, the band where the coldest night of the year averaged 30 to 35°F (-1.1 to 1.7°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.