Frost dates for Los Altos Hills, 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
March 21
typical year
Safe to plant
April 28
frost is over in 9 of 10 years
First fall frost
December 15
typical year
Growing season
275 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 | – | Feb 21 – Mar 7 | – |
| Spinach | – | Feb 7 – 28 | Oct 20 – Nov 3 |
| Lettuce | – | Feb 21 – Mar 14 | Oct 20 – Nov 3 |
| Radishes | – | Feb 21 – Apr 4 | Nov 3 – 17 |
| Onions | – | Feb 21 – Mar 7 | – |
| Potatoes | – | Feb 28 – Mar 14 | – |
| Carrots | – | Feb 28 – Mar 21 | Sep 22 – Oct 6 |
| Beets | – | Feb 21 – Mar 7 | Oct 6 – 20 |
| Kale | Jan 10 – 24 | Feb 21 – Mar 7 | Oct 6 – 20 |
| Broccoli | Jan 10 – 24 | Mar 7 – 21 | Oct 6 – 20 |
| Cabbage | Dec 27 – Jan 10 | Feb 21 – Mar 7 | Oct 6 – 20 |
| Garlic | – | – | Nov 3 – 24 |
| Warm-season crops | |||
| Tomatoes | Mar 3 – 17 | Apr 28 – May 12 | – |
| Peppers | Feb 24 – Mar 10 | May 5 – 19 | – |
| Cucumbers | – | Apr 28 – May 19 | – |
| Zucchini | – | Apr 28 – May 26 | – |
| Pumpkins | – | Apr 28 – May 19 | – |
| Green beans | – | Apr 28 – Oct 6 | – |
| Sweet corn | – | Apr 28 – May 26 | – |
| Basil | Mar 24 – Apr 7 | May 5 – 12 | – |
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 | April 28 | March 21 | January 19 |
| Fall frost before | November 21 | December 15 | January 30 |
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 January 29 (March 30 in a late year), and the first one in fall around January 4.
Towns that use these dates
This is the nearest NOAA station with frost records for 2 towns.
Los Altos Hills, Portola Valley
Where these dates come from
NOAA weather station SKYLINE RIDGE PRESERVE, CA US (USC00048273), 1991–2020 climate normals. It's the nearest station for 5 zip codes, all within 6 miles:
94020, 94021, 94022, 94060, 95014
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.