Frost dates in Anchorage, AK
Direct answer. In Anchorage, AK, the nearest qualified NOAA station is ANCHORAGE MERRILL FLD, AK US (USW00026409), 1.5 miles from the city point. The median last 32°F date is May 1, and the median first 32°F date is September 29, from the 1991–2020 U.S. Climate Normals. The 2023 PRISM ZIP table has no zone for this city within the distance rules, so this page does not show a USDA zone.
Population in the Census 2024 estimate is 289,600. The station is ANCHORAGE MERRILL FLD, AK US (USW00026409).
The 2023 USDA ZIP table does not include Alaska or Hawaii, so Anchorage is shown with frost dates and without a zone. The station below is the nearest qualified NOAA station.
Outside the median season Growing seasonTicks: 10%, 50%, and 90%
Last 32°F in spring
NCEI’s probability is the chance the last spring minimum of 32°F or lower occurs on or after the date.
| Probability | Date | How to read it |
|---|---|---|
| 90% | April 19 | Earlier date. A last 32°F on or after this day is common. |
| 50% | May 1 | Median. |
| 10% | May 9 | Later date. A last 32°F on or after this day is uncommon. |
First 32°F in fall
NCEI’s probability is the chance the first autumn minimum of 32°F or lower occurs on or before the date.
| Probability | Date | How to read it |
|---|---|---|
| 10% | September 17 | Earlier date. A first 32°F on or before this day is uncommon. |
| 50% | September 29 | Median. |
| 90% | October 12 | Later date. A first 32°F on or before this day is common. |
32°F growing-season length
Days between the last spring 32°F and the first autumn 32°F. The figure is a length the season meets or exceeds at that probability, from NCEI, not a subtraction done on this site.
| Probability the season is at least this long | Days |
|---|---|
| 10% | 167 |
| 50% | 150 |
| 90% | 135 |
28°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | May 1 | April 19 | April 10 |
| First, on or before | September 27 | October 8 | October 21 |
| Season at least | 188 days | 172 days | 156 days |
36°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | May 23 | May 12 | May 2 |
| First, on or before | September 7 | September 20 | September 30 |
| Season at least | 144 days | 129 days | 113 days |
Station ANCHORAGE MERRILL FLD, AK US (USW00026409). Completeness flag R, 23 years used for the 32°F dates. NCEI’s annual probability of at least one day at or below 32°F is 100%. Freeze dates are conditional on that threshold occurring. Elevation 42.1 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.
Questions
- When is the last spring frost in Anchorage, AK?
- The median last 32°F date at the station on this page is May 1. NOAA’s 1991–2020 normals give a 50% chance the last spring minimum of 32°F or lower occurs on or after that date. The 90% date is April 19. The 10% date, the later one, is May 9. These are normals, not a forecast for this spring.
- What USDA zone is Anchorage, AK?
- No USDA zone is shown. The 2023 PRISM ZIP table does not include Alaska or Hawaii, and a zone is not borrowed from another state. Frost dates still come from the nearest qualified NOAA 1991–2020 station, 1.5 miles from the city point. The station is named above. The zone and the frost date answer different questions.
- How far away is the weather station?
- The station named on this page is 1.5 miles from the city point in a straight line. Frost dates are 1991–2020 NOAA climate normals for that instrument. They are not a National Weather Service forecast for one night, and they are not the temperature in every yard. The page names the station so the miles stay attached to the dates.