Frost dates for Palo Alto, CA
At Palo Alto, the median last spring frost (32°F) is Feb 1 and the median first fall frost is Dec 7, for a typical growing season of 310 days. For a 90% chance that the last frost has passed, wait until Mar 4. Nearby ZIP codes are in USDA hardiness zones 9b to 10a.
- Feb 1Last spring frost (median)50% chance of 32°F after this date
- Mar 4Safer planting date10% chance of 32°F after this date
- Dec 7First fall frost (median)50% chance of 32°F by this date
- 310 daysGrowing season (median)between 32°F freezes
Last spring frost dates
The chance that the temperature drops to the threshold after each date.
| Temperature | 90% chance later | 50% chance later | 10% chance later |
|---|---|---|---|
| 36°F | Feb 5 | Mar 11 | Apr 15 |
| 32°F | Dec 28 | Feb 1 | Mar 4 |
| 28°F | Dec 15 | Jan 4 | Feb 17 |
| 24°F | Dec 9 | Dec 30 | Feb 14 |
First fall frost dates
The chance that the temperature has dropped to the threshold by each date.
| Temperature | 10% chance by | 50% chance by | 90% chance by |
|---|---|---|---|
| 36°F | Nov 3 | Nov 21 | Dec 8 |
| 32°F | Nov 20 | Dec 7 | Jan 6 |
| 28°F | Dec 3 | Dec 22 | Jan 25 |
| 24°F | Dec 7 | Dec 28 | Feb 12 |
Growing season length
Days between the last spring and first fall freeze, as the length reached in 9, 5 and 1 out of 10 years.
| Temperature | 9 in 10 years at least | 5 in 10 years at least | 1 in 10 years at least |
|---|---|---|---|
| 36°F | 214 days | 252 days | 292 days |
| 32°F | 272 days | 310 days | 347 days |
| 28°F | 318 days | 358 days | 365 days |
| 24°F | 365 days | 365 days | 365 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 96% |
| 28°F | 60% |
| 24°F | 13% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 94301 | 9b | 25 to 30°F | 1 km |
| 94303 | 10a | 30 to 35°F | 3 km |
| 94306 | 9b | 25 to 30°F | 3 km |
| 94025 | 9b | 25 to 30°F | 4 km |
| 94305 | 9b | 25 to 30°F | 4 km |
| 94304 | 9b | 25 to 30°F | 6 km |
Not the official USDA Plant Hardiness Zone Map. Zones shown here are the values published in the USDA-ARS / Oregon State University PRISM Group 2023 ZIP code tables, shown unaltered. For the official interactive map, visit planthardiness.ars.usda.gov.
About this station
- NOAA station ID USC00046646, at 37.4436, -122.1403, elevation 8 m (25 ft).
- Data quality: Representative (10+ years), 18 years of freeze data.
- Average days per year at or below 32°F: 14.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Moffett Federal Airfield (9 km)
- Redwood City (9 km)
- Woodside Fire Station 1 (10 km)
- Newark (12 km)
- Skyline Ridge Preserve (15 km)
- Fremont (16 km)
- San Jose (21 km)
- San Jose (23 km)
Sources
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020, annual/seasonal normals by station (version 1.0.1), file dated June 27, 2023; documentation.
- USDA Agricultural Research Service and PRISM Group, Oregon State University, 2023 Plant Hardiness Zone Map ZIP code tables (CONUS, Alaska, Hawaii, Puerto Rico), files dated November 17, 2023. Data © PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed November 1, 2026. Official map: planthardiness.ars.usda.gov.
- U.S. Census Bureau, 2024 Gazetteer ZIP Code Tabulation Areas file, dated August 30, 2024 (ZIP centroids used to find the nearest station).
Freeze dates are 30-year probabilities, not forecasts. Check your local forecast before planting tender plants.