Frost Dates for 99824 — Douglas, Alaska

Half of springs at Juneau Dwtn, AK see their last 32°F night by April 20; only one in ten is past it by April 5, and one in ten still has one after May 5. Planting tender crops after April 26 leaves a 30% risk of a frost on them, after April 30 20%, and after May 5 10%. The 15 days between the even-odds date and the one-in-ten date is wider than at 70% of the 37 Alaska stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 22 in half of years, as early as October 5 one year in ten, and holds off past November 7 one year in ten. A hard freeze of 28°F follows 17 days later, around November 8; in spring the one-in-ten date for 28°F is April 16, 19 days before the 32°F one. The freeze-free season lasts 183 days in a typical year, longer than at 95% of the 37 Alaska stations; it reaches 205 days one year in ten and falls short of 162 one year in ten. On average 105 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 17 days longer, to about May 7, and return around October 6. Severe cold of 16°F or below comes in 97% of winters, usually between December 17 and February 25.

July is the warmest month at Juneau Dwtn, AK, averaging 63°F by day and 52°F at night; January is the coldest at 34°F and 27°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 18% of years.

Warmth for growing adds up to 750 growing degree days a year (base 50°F), more than at 57% of the 37 Alaska stations. 33% of them (249) have built up by the end of June, and July adds the most, 229.

The nearest other station, Juneau International Airport, AK, 8 miles northwest of Douglas, has a last frost 14 days later (May 4), a first frost 19 days earlier (October 3), a season 33 days shorter.

The first measurable snow (0.1 inch or more) in Douglas usually arrives around November 5, and the last of the season around March 31. Those are the middle dates across the winters of 1991–2020 at Juneau International Airport, AK, 8.2 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 20 days after the last snow.

ZIP 99824 is 2 miles from Juneau Dwtn, AK, which stands at 50 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 99824 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°C) over 1991–2020; a zone describes winter lows, not frost dates.