Frost Dates for 99827 — Haines, Alaska

Half of springs at Haines Airport, AK see their last 32°F night by April 25; only one in ten is past it by April 10, and one in ten still has one after May 7. Planting tender crops after April 30 leaves a 30% risk of a frost on them, after May 3 20%, and after May 7 10%. The 12 days between the even-odds date and the one-in-ten date is narrower than at 65% of the 37 Alaska stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 12 in half of years, as early as September 30 one year in ten, and holds off past October 29 one year in ten. A hard freeze of 28°F follows 17 days later, around October 29; in spring the one-in-ten date for 28°F is April 22, 15 days before the 32°F one. The freeze-free season lasts 172 days in a typical year, longer than at 92% of the 37 Alaska stations; it reaches 192 days one year in ten and falls short of 152 one year in ten. On average 134 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 14 days longer, to about May 9, and return around September 30. Severe cold of 16°F or below comes every winter, usually between November 24 and March 11.

July is the warmest month at Haines Airport, AK, averaging 65°F by day and 52°F at night; January is the coldest at 30°F and 19°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 28% of years.

Warmth for growing adds up to 863 growing degree days a year (base 50°F), more than at 81% of the 37 Alaska stations. 32% of them (280) have built up by the end of June, and July adds the most, 271. Precipitation totals 47.6 inches a year, most in December (7.1") and least in June (1.6"); May to September bring 30% of it.

The first measurable snow (0.1 inch or more) in Haines usually arrives around November 1, and the last of the season around April 4. Those are the middle dates across the winters of 1991–2020 at Haines #2, AK, 6.4 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 21 days after the last snow.

ZIP 99827 is 4 miles from Haines Airport, AK, which stands at 15 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 99827 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°C) over 1991–2020; a zone describes winter lows, not frost dates.