Frost dates for Union City, CA
When the last spring frost and first fall frost usually come, and when to plant, from 30 years of NOAA weather records.
Last spring frost
January 7
typical year
Safe to plant
February 7
frost is over in 9 of 10 years
First fall frost
December 22
typical year
Growing season
353 days
frost-free, typical year
Frost watch this week
Tonight's and the next six nights' lows from the National Weather Service forecast for the station's location. Frost: 32°F or colder. Possible frost: 33–36°F, mostly in low spots on clear, still nights.
When to plant
Counted from this page's frost dates. Warm-season crops wait for the safe-to-plant date.
| Crop | Start indoors | Plant outside | Fall planting |
|---|---|---|---|
| Cool-season crops | |||
| Peas | – | Dec 10 – 24 | – |
| Spinach | – | Nov 26 – Dec 17 | Oct 27 – Nov 10 |
| Lettuce | – | Dec 10 – 31 | Oct 27 – Nov 10 |
| Radishes | – | Dec 10 – Jan 21 | Nov 10 – 24 |
| Onions | – | Dec 10 – 24 | – |
| Potatoes | – | Dec 17 – 31 | – |
| Carrots | – | Dec 17 – Jan 7 | Sep 29 – Oct 13 |
| Beets | – | Dec 10 – 24 | Oct 13 – 27 |
| Kale | Oct 29 – Nov 12 | Dec 10 – 24 | Oct 13 – 27 |
| Broccoli | Oct 29 – Nov 12 | Dec 24 – Jan 7 | Oct 13 – 27 |
| Cabbage | Oct 15 – 29 | Dec 10 – 24 | Oct 13 – 27 |
| Garlic | – | – | Nov 10 – Dec 1 |
| Warm-season crops | |||
| Tomatoes | Dec 13 – 27 | Feb 7 – 21 | – |
| Peppers | Dec 6 – 20 | Feb 14 – 28 | – |
| Cucumbers | – | Feb 7 – 28 | – |
| Zucchini | – | Feb 7 – Mar 7 | – |
| Pumpkins | – | Feb 7 – 28 | – |
| Green beans | – | Feb 7 – Oct 13 | – |
| Sweet corn | – | Feb 7 – Mar 7 | – |
| Basil | Jan 3 – 17 | Feb 14 – 21 | – |
Onions: from sets. Green beans: until 10 weeks before the first fall frost. Garlic: harvest next summer.
The year at a glance
Start indoors Plant outside Fall planting
The chance of frost, by date
| 1 year in 10 | Half of years | 9 years in 10 | |
|---|---|---|---|
| Spring frost after | February 7 | January 7 | December 14 |
| Fall frost before | December 2 | December 22 | January 21 |
Frost here means 32°F or colder. Read across: in 1 year in 10, spring frost carries on past the first date, which is why that date is the safe-to-plant date.
Hard freeze (28°F)
A hard freeze kills most garden plants, even hardy ones. The last one in spring usually comes around December 31 (January 20 in a late year), and the first one in fall around December 29.
Towns that use these dates
This is the nearest NOAA station with frost records for 1 town.
Union City
Where these dates come from
NOAA weather station FREMONT, CA US (USC00043244), 1991–2020 climate normals. It's the nearest station for 3 zip codes, all within 6 miles:
94536, 94539, 94587
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.