Frost Dates for 99567 — Chugiak, Alaska

Half of springs at Eklutna Wtp, AK see their last 32°F night by May 18; only one in ten is past it by May 6, and one in ten still has one after May 30. Planting tender crops after May 23 leaves a 30% risk of a frost on them, after May 26 20%, and after May 30 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 September 20 in half of years, as early as September 4 one year in ten, and holds off past October 4 one year in ten. A hard freeze of 28°F follows 10 days later, around September 30; in spring the one-in-ten date for 28°F is May 15, 15 days before the 32°F one. The freeze-free season lasts 124 days in a typical year, shorter than at 59% of the 37 Alaska stations; it reaches 142 days one year in ten and falls short of 104 one year in ten. On average 205 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 June 1, and return around September 8. Severe cold of 16°F or below comes every winter, usually between October 26 and April 4.

July is the warmest month at Eklutna Wtp, AK, averaging 71°F by day and 50°F at night; January is the coldest at 21°F and 8°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month.

Warmth for growing adds up to 847 growing degree days a year (base 50°F), more than at 78% of the 37 Alaska stations. 31% of them (259) have built up by the end of June, and July adds the most, 311. Precipitation totals 16.6 inches a year, most in August (2.8") and least in April (0.5"); May to September bring 55% of it.

The nearest other station, Eagle Rvr Gakona Circle, AK, 8 miles southwest of Chugiak, has a last frost 9 days earlier (May 9), a first frost 6 days later (September 26), a season 15 days longer.

The first measurable snow (0.1 inch or more) in Chugiak usually arrives around October 26, and the last of the season around April 4. Those are the middle dates across the winters of 1991–2020 at Eklutna Wtp, AK, 4.2 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 44 days after the last snow.

ZIP 99567 is 4 miles from Eklutna Wtp, AK, which stands at 640 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 99567 in zone 5a, the band where the coldest night of the year averaged -20 to -15°F (-28.9 to -26.1°C) over 1991–2020; a zone describes winter lows, not frost dates.