Fairbanks, Alaska: planting zone & frost dates
Fairbanks is in USDA plant hardiness zone 2a, where the average coldest winter night reaches -50 to -45°F (-45.6 to -42.8°C). The typical last spring frost is around May 21 and the first fall frost around Sep 1.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | May 29 | Aug 25 |
| Typical planning date (30% risk) | May 21 | Sep 1 |
| Median (50%) | May 16 | Sep 6 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station AURORA, AK (USC00500490), 2.4 mi (3.9 km) from the city center and 3 ft lower than the city center (-1 m). Record used for the 1991–2020 normals: 17 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Fairbanks
Fairbanks spans more than one half-zone. Share of the city's land area by zone (via its 4 ZIP codes): 2a (36%), 3a (33%), 3b (30%). The headline zone is the one covering the most land. Look up your ZIP for your exact zone.
Vegetable planting calendar for Fairbanks
Dates are counted from the 30%-risk frost dates above (last frost May 21, first frost Sep 1). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato Short season (103 frost-free days): choose early varieties. | Mar 26 – Apr 9 | May 28 – Jun 11 | — | — |
| Pepper Short season (103 frost-free days): choose early varieties. | Mar 12 – Mar 26 | Jun 4 – Jun 18 | — | — |
| Lettuce | Apr 9 – Apr 23 | May 7 – May 28 | Apr 23 – Jun 4 | Jun 23 – Jul 21 |
| Green Beans | — | — | May 28 – Jul 2 | — |
| Sweet Corn Short season (103 frost-free days): choose early varieties. | — | — | May 28 – Jun 25 | — |
| Zucchini & Summer Squash | Apr 23 – Apr 30 | May 28 – Jun 11 | May 28 – Jun 18 | — |
| Cucumber | Apr 23 – Apr 30 | Jun 4 – Jun 11 | May 28 – Jun 18 | — |
| Carrot | — | — | Apr 30 – Jun 4 | — |
| Onion | Feb 26 – Mar 12 | Apr 23 – May 7 | — | — |
| Potato | — | Apr 23 – May 14 | — | — |
| Basil Short season (103 frost-free days): choose early varieties. | Apr 9 – Apr 23 | Jun 4 – Jun 18 | Jun 4 – Jun 25 | — |
| Spinach | — | — | Apr 9 – May 7 | Jul 7 – Aug 4 |
| Kale | Mar 26 – Apr 9 | Apr 23 – May 14 | Apr 23 – May 14 | Jun 23 – Jul 21 |
| Broccoli | Mar 26 – Apr 9 | May 7 – May 28 | — | — |
| Peas | — | — | Apr 9 – Apr 30 | Jun 23 – Jul 7 |
| Eggplant Short season (103 frost-free days): choose early varieties. | Mar 12 – Mar 26 | Jun 4 – Jun 18 | — | — |
| Cabbage | Mar 26 – Apr 9 | Apr 23 – May 7 | — | — |
| Radish | — | — | Apr 16 – Jun 4 | Jul 21 – Aug 18 |
| Strawberry | — | Apr 23 – May 14 | — | — |
| Beets | — | — | Apr 30 – Jun 11 | Jun 23 – Jul 7 |
Nearby cities in Alaska
- Anchorage — zone 5a, last frost May 4, first frost Sep 24
More: all Alaska cities
Fairbanks gardening questions
When is the last frost in Fairbanks, AK?
Plan around May 21. At NOAA's Aurora, AK station, 2.4 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by May 16, and after May 29 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around May 7. The last frost is fairly predictable here: only 24 days separate the 90% and 10% dates (median for cities on this site: 36 days).
When should I plant tomatoes in Fairbanks, AK?
Start seeds indoors Mar 26 – Apr 9 and set transplants outside May 28 – Jun 11, once nights stay above 50°F and the soil is near 60°F. The 103 days between the 30% frost dates are tight for full-size tomatoes, so choose early or cherry varieties and your warmest, most sheltered spot. More: tomato planting dates by zone.
How long is the growing season in Fairbanks?
About 112 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 92 days, and in 1 year in 10 it runs 130 days or more. In fall there is a 10% chance of frost by Aug 25 and a 30% chance by Sep 1.
When should I plant a fall garden in Fairbanks?
Count back from the first fall frost (Sep 1): sow kale Jun 23 – Jul 21; sow lettuce Jun 23 – Jul 21; sow radishes Jul 21 – Aug 18. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Sep 18. How the math works: succession and fall planting.
Did Fairbanks's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Fairbanks is zone 2a on both the 2012 and the 2023 USDA maps (PRISM/OSU ZIP listings). About 42% of U.S. ZIP codes kept their half-zone in 2023. Why the 2023 map is warmer.
Is all of Fairbanks in zone 2a?
No. Zone 2a covers about 36% of the city's land; the rest is in 3a (33%), 3b (30%), measured across the city's 4 ZIP codes. Check your own ZIP code in the table above or with the ZIP lookup.