USDA Hardiness Zone 9b
Frost Dates for 94561 — Oakley, California
Averages from Antioch Pumping Plt #3, Ca US, the nearest reporting station, 2.2 miles away.
Plant tender crops after January 12, and expect the first autumn freeze around December 19. That leaves about 343 frost-free days.
- Last spring frost
- January 12
- First fall frost
- December 19
- Growing season
- 343 days
- Hardiness zone
- 9b
50% probability
50% probability
frost-free
25 to 30°F annual low
Planting calendar for 94561
| When | What to do |
|---|---|
| November 3 – November 17 | Start peppers and aubergines indoors They need eight to ten weeks under lights before they can go out. |
| November 17 – December 1 | Start tomatoes indoors Six to eight weeks gives a transplant big enough to set fruit early. |
| December 15 – December 29 | Sow peas, spinach, lettuce, radish outdoors These tolerate light frost and prefer to germinate in cool soil. |
| January 12 onward | Transplant tomatoes, peppers, basil, squash, cucumbers The average last freeze has passed — still watch the actual forecast. |
| by September 26 | Sow the autumn crop of carrots, beets and brassicas They need about twelve weeks to size up before growth stops. |
| by December 5 | Harvest tender crops, or be ready to cover them A first freeze two weeks early is well within normal variation. |
| December 19 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 12 to put tender plants — tomatoes, peppers, basil, squash — in the ground. That is the date by which half of years in Oakley, California are past their last freeze. Harvest before December 19, which leaves roughly 343 frost-free days.
ZIP 94561 sits in USDA hardiness zone 9b, meaning the average coldest night of the year falls between 25 to 30°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.