Frost dates in USDA zone 9a (20 to 25°F)
USDA zone 9a covers places whose coldest winter night averages 20 to 25°F. Across the 363 NOAA weather stations in zone 9a, the median last spring frost is Mar 4, but it ranges from Feb 15 to Mar 30 for most stations. Enter your ZIP for your local date.
- Mar 4Median last spring frostmost stations Feb 15–Mar 30
- Nov 25Median first fall frost50% chance of 32°F by this date
- 267 daysMedian growing seasonbetween 32°F freezes
- 2,199ZIP codes in zone 9a20 to 25°F average coldest night
- 363Stations with frost datesof 363 NOAA stations matched
Earliest and latest last-frost stations in zone 9a
| Station | Last spring frost | First fall frost |
|---|---|---|
| Death Valley National Park, CA | Jan 1 | Dec 19 |
| Borrego Desert Park, CA | Jan 10 | Jan 1 |
| Las Vegas Air Terminal, NV | Jan 24 | Dec 10 |
| Los Banos, CA | Jan 26 | Dec 10 |
| Saguaro National Park, AZ | Jan 26 | Dec 16 |
| Quartzsite, AZ | Jan 28 | Dec 6 |
| Florence, AZ | Jan 30 | Dec 12 |
| Wasco, CA | Jan 31 | Dec 5 |
| Charleston City, SC | Feb 4 | Dec 30 |
| Las Vegas WFO, NV | Feb 4 | Dec 5 |
| Station | Last spring frost | First fall frost |
|---|---|---|
| Burney, CA | Jun 3 | Sep 14 |
| Grant Grove, CA | Jun 1 | Oct 7 |
| So Entrance Yosemite National Park, CA | May 24 | Oct 10 |
| Priest Valley, CA | May 8 | Oct 22 |
| Willits 1 NE, CA | May 5 | Oct 9 |
| Strawberry Valley, CA | May 4 | Oct 30 |
| Campo, CA | Apr 30 | Oct 26 |
| Campo Asos, CA | Apr 29 | Nov 1 |
| Raymond 2 S, WA | Apr 26 | Oct 17 |
| Kitt Peak, AZ | Apr 26 | Nov 4 |
Zone 9a by state
| State | Stations | Median last frost | Median first frost |
|---|---|---|---|
| Alabama | 8 | Mar 5 | Nov 24 |
| Arizona | 26 | Feb 25 | Nov 27 |
| California | 54 | Mar 13 | Nov 22 |
| Florida | 40 | Mar 3 | Nov 28 |
| Georgia | 34 | Mar 9 | Nov 21 |
| Louisiana | 43 | Mar 1 | Nov 25 |
| Mississippi | 11 | Mar 6 | Nov 22 |
| Nevada | 5 | Feb 26 | Nov 22 |
| North Carolina | 4 | Mar 2 | Dec 20 |
| Oregon | 30 | Mar 24 | Nov 18 |
| South Carolina | 7 | Mar 3 | Dec 3 |
| Texas | 87 | Mar 1 | Nov 27 |
| Washington | 14 | Mar 27 | Nov 12 |
Neighboring zones
How these numbers are made
Each ZIP code gets one zone from the USDA-ARS / PRISM 2023 ZIP tables, which use the map’s 1991–2020 average of the coldest winter night of each year. A ZIP code can span more than one zone, and USDA’s own lookup works by ZIP or address. Each NOAA station is assigned the most common zone among the closest ZIP codes listed on its station page (a tie goes to the zone of the closest of those ZIPs). Frost dates are NOAA’s 50%-probability (median) 32°F dates for each station, the same values shown on the station pages. Zone figures are the median, 10th and 90th percentile across stations; a first fall frost in January to June is counted in the following year.
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.
Sources
- 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.
- 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.
- 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.