USDA Hardiness Zone 10a
Frost Dates for 94577 — San Leandro, California
NOAA 1991–2020 normals from Oakland Metro International Airport, CA (6 ft), 4 miles west.
Updated
A freeze (32°F) reaches San Leandro in 63% of winters. When it does, the first fall frost comes around December 23 and the last spring frost around January 7; after February 8 the chance of another is under 6%.
- Last spring frost
- January 7
- First fall frost
- December 23
- Winters with a freeze
- 63%
- Hardiness zone
- 10a
50%, in freezing years
50%, in freezing years
32°F or below, 1991–2020
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 Leandro
In the 63% of winters that bring a 32°F night, half of springs at Oakland Metro International Airport, CA see their last 32°F night by January 7; only one in ten is past it by December 13, and one in ten still has one after February 8. Counting the winters with no freeze at all, the risk of a 32°F night after February 8 is under 6% and after January 7 31%. The 32 days between the even-odds date and the one-in-ten date is wider than at 55% 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 23 in half of years, as early as November 30 one year in ten, and holds off past January 24 one year in ten. A hard freeze of 28°F is less common: it came in 11% of winters. The freeze-free season lasts 356 days in a typical year, longer than at 97% of the 219 California stations; it reaches 365 days one year in ten and falls short of 320 one year in ten. On average 3 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 32 days longer, to about February 8, and return around December 4. No night reached 24°F in 1991–2020.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F98% of yrs | Jan 3 | Jan 17 | Jan 27 | Feb 2 | Feb 8 | Feb 16 | Feb 21 | Feb 28 | Mar 7 |
| 32°F63% of yrs | Dec 13 | Dec 24 | Dec 29 | Jan 2 | Jan 7 | Jan 14 | Jan 22 | Jan 30 | Feb 8 |
| 28°F11% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F98% of yrs | Nov 15 | Nov 21 | Nov 27 | Dec 1 | Dec 4 | Dec 7 | Dec 14 | Dec 23 | Jan 5 |
| 32°F63% of yrs | Nov 30 | Dec 6 | Dec 10 | Dec 16 | Dec 23 | Dec 29 | Jan 3 | Jan 10 | Jan 24 |
| 28°F11% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Oakland Metro International Airport, 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 94577 →Compare San Leandro with another place →
Weather by month in San Leandro
September is the warmest month at Oakland Metro International Airport, CA, averaging 74°F by day and 56°F at night; January is the coldest at 58°F and 42°F. From March to November the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 11% of years.
Warmth for growing adds up to 3,106 growing degree days a year (base 50°F), fewer than at 82% of the 283 California stations. 39% of them (1,212) have built up by the end of June, and August adds the most, 454. Precipitation totals 18.6 inches a year, most in December (3.8") and least in July (0.0"); May to September bring 5% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 58 | 42 | 3.4 | 35% | 1 | 48 |
| Feb | 60 | 45 | 3.5 | 11% | <1 | 90 |
| Mar | 63 | 47 | 2.7 | 0% | 0 | 164 |
| Apr | 66 | 49 | 1.4 | 0% | 0 | 221 |
| May | 68 | 52 | 0.6 | 0% | 0 | 307 |
| Jun | 71 | 54 | 0.2 | 0% | 0 | 383 |
| Jul | 72 | 56 | 0.0 | 0% | 0 | 431 |
| Aug | 72 | 57 | 0.0 | 0% | 0 | 454 |
| Sep | 74 | 56 | 0.1 | 0% | 0 | 444 |
| Oct | 72 | 51 | 0.9 | 0% | 0 | 352 |
| Nov | 64 | 46 | 2.0 | 6% | <1 | 157 |
| Dec | 58 | 42 | 3.8 | 36% | 1 | 56 |
Monthly normals 1991–2020 at Oakland Metro International Airport, CA (6 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, Hayward Air Terminal, CA, 5 miles southeast of San Leandro, has a 32°F night in 45% of winters against 63% here, and a coolest-month low 1°F warmer (43°F).
When it snows in San Leandro, California
Measurable snow is rare here: only 0 of 19 winters from 1991 to 2020 recorded 0.1 inch or more at Upper San Leandro Filters, CA, 3.5 miles away, so there is no typical first-snow date to plan around.
Where these figures come from
ZIP 94577 is 4 miles from Oakland Metro International Airport, CA, which stands at 6 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 4 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 94577 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.