USDA Hardiness Zone 9b
Frost Dates for 95391 — Mountain House, California
Averages from Tracy Pumping Plt, Ca US, the nearest reporting station, 3.6 miles away.
Plant tender crops after January 19, and expect the first autumn freeze around December 10. That leaves about 330 frost-free days.
- Last spring frost
- January 19
- First fall frost
- December 10
- Growing season
- 330 days
- Hardiness zone
- 9b
50% probability
50% probability
frost-free
25 to 30°F annual low
Planting calendar for 95391
| When | What to do |
|---|---|
| November 10 – November 24 | Start peppers and aubergines indoors They need eight to ten weeks under lights before they can go out. |
| November 24 – December 8 | Start tomatoes indoors Six to eight weeks gives a transplant big enough to set fruit early. |
| December 22 – January 5 | Sow peas, spinach, lettuce, radish outdoors These tolerate light frost and prefer to germinate in cool soil. |
| January 19 onward | Transplant tomatoes, peppers, basil, squash, cucumbers The average last freeze has passed — still watch the actual forecast. |
| by September 17 | Sow the autumn crop of carrots, beets and brassicas They need about twelve weeks to size up before growth stops. |
| by November 26 | Harvest tender crops, or be ready to cover them A first freeze two weeks early is well within normal variation. |
| December 10 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 19 to put tender plants — tomatoes, peppers, basil, squash — in the ground. That is the date by which half of years in Mountain House, California are past their last freeze. Harvest before December 10, which leaves roughly 330 frost-free days.
ZIP 95391 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.