Frost Dates for Port San Juan, AK

Elevation: 12 m

Frost Dates

Last Spring Frost (50%) A 50% chance that the last spring frost has already passed by this date. Most gardeners use this as their primary planting guide. May 10
First Fall Frost (50%) A 50% chance that the first fall frost has occurred by this date. Plan to harvest or protect tender plants before this date. October 7

30% Probability

Only a 30% chance of frost remaining by this date. Use these dates for a safer planting window, especially for tender plants sensitive to cold.
Last Spring Frost May 17
First Fall Frost October 2

Hard Freeze (28°F)

Last Spring Hard Freeze April 23
First Fall Hard Freeze October 25
60.05°N, 148.07°W © OpenStreetMap

Growing Season

150 Days May 10 to October 7

USDA Hardiness Zone

Hardiness zones indicate which perennial plants can survive winter in your area. For annual vegetables, frost dates and growing season length matter more than hardiness zone.
Zone 7b

Avg. annual minimum: 5 to 10°F

Learn more

Köppen Climate

The Köppen climate classification system categorizes climates based on temperature and precipitation patterns.
Dfc Subarctic

Short, cool summers and long, very cold winters. Growing seasons of 3–4 months require fast-maturing varieties. Root vegetables, potatoes, and cold-hardy greens are the most reliable.

Köppen climate map

Temperature

Avg High Avg Temp Avg Low Light Frost (32°F) Hard Frost (28°F)
Temperature table
Average monthly temperatures (°F)
Month Avg High Avg Temp Avg Low
January34°30°26°
February35°31°26°
March36°31°26°
April43°37°32°
May52°45°37°
June59°52°44°
July63°56°50°
August61°55°49°
September54°49°44°
October45°41°36°
November38°34°30°
December36°32°28°

Precipitation

Precipitation table
Average monthly precipitation (inches)
MonthPrecipitation
January13.0
February10.9
March11.0
April10.5
May8.6
June5.2
July6.3
August11.4
September16.0
October17.4
November16.8
December15.4

Sunrise / Sunset

Daylight Longest: 18h 31m · Shortest: 5h 29m
Sunrise and sunset table
Sunrise, sunset, and daylight on the 15th of each month (local solar time)
Month Sunrise Sunset Daylight
January8:50 AM3:10 PM6h 20m
February7:37 AM4:23 PM8h 46m
March6:20 AM5:40 PM11h 21m
April4:53 AM7:07 PM14h 14m
May3:35 AM8:25 PM16h 50m
June2:46 AM9:14 PM18h 27m
July3:07 AM8:53 PM17h 45m
August4:19 AM7:41 PM15h 22m
September5:45 AM6:15 PM12h 31m
October7:08 AM4:52 PM9h 43m
November8:28 AM3:32 PM7h 04m
December9:14 AM2:46 PM5h 32m

Nearby Stations

Main Bay, AKMay 19 - October 6 Seward AP, AKMay 2 - October 7 Seward 19n, AK May 21 - September 26 Wally Noerenberg Hatchery, AK May 20 - October 9 Whittier, AKApril 25 - October 14 Seward 8 Nw, AK

Plan Your Garden with Planter

Now that you know your frost dates, use Planter to plan your veggie garden! Planter is an easy drag-and-drop garden planner with personalized planting schedules.

Try Planter For Free

Available everywhere: iOS, Android, web, and more!

Planter app garden planner preview