USDA Hardiness Zone 10a
Frost Dates for 94803 — El Sobrante, California
Averages from Richmond, Ca US, the nearest reporting station, 5.7 miles away.
Plant tender crops after January 4, and expect the first autumn freeze around January 2. That leaves about 365 frost-free days.
- Last spring frost
- January 4
- First fall frost
- January 2
- Growing season
- 365 days
- Hardiness zone
- 10a
50% probability
50% probability
frost-free
30 to 35°F annual low
Planting calendar for 94803
| When | What to do |
|---|---|
| October 26 – November 9 | Start peppers and aubergines indoors They need eight to ten weeks under lights before they can go out. |
| November 9 – November 23 | Start tomatoes indoors Six to eight weeks gives a transplant big enough to set fruit early. |
| December 7 – December 21 | Sow peas, spinach, lettuce, radish outdoors These tolerate light frost and prefer to germinate in cool soil. |
| January 4 onward | Transplant tomatoes, peppers, basil, squash, cucumbers The average last freeze has passed — still watch the actual forecast. |
| by October 10 | Sow the autumn crop of carrots, beets and brassicas They need about twelve weeks to size up before growth stops. |
| by December 19 | Harvest tender crops, or be ready to cover them A first freeze two weeks early is well within normal variation. |
| January 2 onward | Plant garlic, mulch beds, lift tender bulbs Garlic wants a cold spell; bare soil loses structure over winter. |
What these dates mean
Wait until after January 4 to put tender plants — tomatoes, peppers, basil, squash — in the ground. That is the date by which half of years in El Sobrante, California are past their last freeze. Harvest before January 2, which leaves roughly 365 frost-free days.
ZIP 94803 sits in USDA hardiness zone 10a, meaning the average coldest night of the year falls between 30 to 35°F. Zone decides what survives the winter; frost dates decide when to plant each spring. They are different questions, and a plant can pass one and fail the other.
These are thirty-year NOAA averages for 1991–2020, not a forecast. Any individual year can frost two to three weeks either side of these dates, so check the actual forecast before planting out.