Frost dates for Fairbanks, Alaska
In Fairbanks, half of springs have had their last frost by May 13 (and 1 spring in 10 still has one after May 26), and half of falls have had their first frost by September 13, leaving about 121 frost-free days in a typical year. Here is how sure those dates are, what they mean for planting, and where they come from.
Frost dates for
Fairbanks, Alaska
Last spring frost
May 13
Half of springs have their last frost by this date. For a safer bet, wait until May 26: only 1 spring in 10 has a frost after that.
First fall frost
September 13
Half of falls have their first frost by this date. In 1 fall in 10 it comes by August 29.
Growing season
121 days
Frost-free days in a typical year. 9 years in 10 get at least 102.
Hardiness zone
3a
2023 USDA map: the coldest night of winter averages −40°F to −35°F. On the 2012 map it was 2a, a full zone colder. ZIP codes within about 6 miles of the city's center: 1 in 2a, 1 in 2b and 1 in 3a.
Stations near you disagree. NOAA's Fairbanks International Airport (7 miles away, at 430 feet above sea level), the one we used, gives a typical last frost of May 13 and a typical first frost of September 13. NOAA's Fox 2 SE (8 miles away, at 770 feet above sea level) gives a typical last frost of May 28 and a typical first frost of September 1. So the typical last frost could fall anywhere from May 13 to 28 and the typical first frost from September 1 to 13, depending on whether your garden is more like one or the other. Local terrain matters: hillsides, valley floors, water and city heat can change frost dates a lot over a few miles. Treat the dates here as a starting point, and compare with a nearby gardener or your county extension office.
Print a year planner for Fairbanks
Frost risk through the year
How sure are these dates?
A frost date is a probability, not a promise. NOAA worked out, from 30 years of nightly lows, how often the last spring frost and the first fall frost fall on each date. The middle column is the typical year. The outer columns are the early and late years that come about once a decade.
| Early year 1 in 10 | Typical year 1 in 2 | Late year 1 in 10 | |
|---|---|---|---|
| Last frost in spring | May 2 | May 13 | May 26 |
| First frost in fall | August 29 | September 13 | September 24 |
The frost-free season between them runs 121 days in a typical year. In 1 year in 10 it is 138 days or longer, and in 1 year in 10 it is 102 days or shorter.
- Hard freeze (28°F): typically last on May 4 and first on September 23. It is a harder freeze than the 32°F frost line, cold enough to damage many garden plants; how hardy a crop is decides whether it comes through. (The National Weather Service's own hard-freeze threshold varies from office to office.)
- Frost possible (36°F at the station): typically last on May 22 and first on September 1. On clear, still nights the ground can be several degrees colder than the thermometer, so frost can form on plants when the official reading is in the mid-30s.
In 8 springs out of 10, the last frost in Fairbanks comes between May 2 and May 26, a window of 24 days. That is narrower than at most NOAA stations (the typical window is 31 days), so the typical date is a steadier guide here than in most places.
Among Alaska's 163 NOAA stations with a frost every year, 57 percent have their typical last frost later than Fairbanks does.
Planting calendar for Fairbanks
These dates count from the typical last and first frosts, using the planting rules published by Colorado State University Extension (spring), Virginia Cooperative Extension (fall crops) and University of Minnesota Extension (garlic, where winters are hard). Weather in any one year can run early or late, so check the forecast before you plant tender crops.
Your season is too short for a separate fall planting of cabbage and broccoli: sown late enough to be a fall crop, it wouldn't be ready before the typical first frost. Your spring planting is your harvest.
| When | What to do | Why then |
|---|---|---|
| February | ||
| February 25 to March 25 | Broccoli and cabbage Start seeds indoors | 5 to 7 weeks before planting them out |
| March | ||
| March 11 to April 8 | Cauliflower Start seeds indoors | 5 to 7 weeks before planting out |
| March 25 to April 15 | Eggplant Start seeds indoors | 6 to 9 weeks before planting out |
| April | ||
| April 1 to 15 | Peppers Start seeds indoors | 6 to 8 weeks before planting out |
| April 8 to 22 | Tomatoes Start seeds indoors | 5 to 7 weeks before planting out |
| April 15 to 29 | Peas, spinach, lettuce, radishes, onion sets, turnips Sow outdoors, as early as | hardy crops: 2 to 4 weeks before the typical last frost |
| April 15 to 29 | Broccoli and cabbage Plant out, as early as | hardy crops: 2 to 4 weeks before the typical last frost |
| April 29 to May 13 | Beets, carrots, potatoes, Swiss chard Plant outdoors, as early as | semi-hardy crops: up to 2 weeks before the typical last frost |
| April 29 to May 13 | Cauliflower Plant out, as early as | semi-hardy: up to 2 weeks before the typical last frost |
| May | ||
| May 13 | Snap beans, sweet corn, cucumbers, summer squash Sow outdoors around | tender crops: around the typical last frost date |
| May 27 | Tomatoes, peppers, eggplant Plant out from | very tender: 2 weeks or more after the typical last frost |
| May 27 | Melons, winter squash, pumpkins, lima beans Sow outdoors from | very tender: 2 weeks or more after the typical last frost |
| June | ||
| June 17 | Snap beans for fall Last date to sow | 60 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| June 21 | Carrots for fall Last date to sow | 70 days to harvest, plus 2 weeks for slower fall growth |
| June 22 | Cucumbers for fall Last date to sow | 55 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| June 26 | Peas for fall Last date to sow | 65 days to harvest, plus 2 weeks for slower fall growth |
| June 27 | Summer squash for fall Last date to sow | 50 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| July | ||
| July 1 | Leaf lettuce and beets for fall Last date to sow | 60 days to harvest, plus 2 weeks for slower fall growth |
| July 11 | Turnips and kohlrabi for fall Last date to sow | 50 days to harvest, plus 2 weeks for slower fall growth |
| July 21 | Spinach for fall Last date to sow | 40 days to harvest, plus 2 weeks for slower fall growth |
| July 31 | Radishes for fall Last date to sow | 30 days to harvest, plus 2 weeks for slower fall growth |
| August | ||
| August 29 | Tomatoes, peppers, squash, melons, cucumbers Watch the forecast from | in 1 fall in 10 the first frost comes by this date; pick tender crops before a frost |
| September | ||
| September 30 to October 7 | Garlic Plant cloves | one or two weeks after the typical first hard freeze (28°F), our reading of the first killing frost |
Want more insurance? Shift every spring date 13 days later. That plans around May 26, the date after which only 1 spring in 10 has a frost.
For spring bulbs such as tulips and daffodils, plant once the soil has cooled to about 50 to 55°F and keep going until a couple of weeks before the ground freezes. Our guide to fall planting explains how to tell.
Where these numbers come from
These dates come from NOAA's weather station Fairbanks International Airport (station USW00026411), 7 miles from the center of Fairbanks. It sits at about the same elevation, 430 feet above sea level. NOAA rates this station's record as standard: at least 24 of the 30 years, with gaps filled from nearby stations.
See frost dates across Alaska, or look up your own ZIP code for the station nearest you. Want the background? Read what a last frost date really means.