Frost Dates for 99577 — Eagle River, Alaska

Half of springs at Eagle Rvr Gakona Circle, AK see their last 32°F night by May 9; only one in ten is past it by April 29, and one in ten still has one after May 22. Planting tender crops after May 14 leaves a 30% risk of a frost on them, after May 17 20%, and after May 22 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 46% of the 37 Alaska stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 26 in half of years, as early as September 12 one year in ten, and holds off past October 10 one year in ten. A hard freeze of 28°F follows 11 days later, around October 7; in spring the one-in-ten date for 28°F is May 7, 15 days before the 32°F one. The freeze-free season lasts 139 days in a typical year, longer than at 57% of the 37 Alaska stations; it reaches 157 days one year in ten and falls short of 120 one year in ten. On average 191 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 15 days longer, to about May 24, and return around September 15. Severe cold of 16°F or below comes every winter, usually between November 1 and April 1.

July is the warmest month at Eagle Rvr Gakona Circle, AK, averaging 67°F by day and 50°F at night; January is the coldest at 20°F and 9°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 85% of years.

Warmth for growing adds up to 662 growing degree days a year (base 50°F), more than at 51% of the 37 Alaska stations. 30% of them (201) have built up by the end of June, and July adds the most, 264. Precipitation totals 17.7 inches a year, most in August (2.8") and least in April (0.6"); May to September bring 54% of it.

The nearest other station, Fort Richardson Wtp, AK, 7 miles southwest of Eagle River, has the same 50% last-frost date, the same first-frost date, a season 1 day shorter.

The first measurable snow (0.1 inch or more) in Eagle River usually arrives around October 20, and the last of the season around April 8. Those are the middle dates across the winters of 1991–2020 at Eagle Rvr Gakona Circle, AK, 1.1 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 31 days after the last snow.

ZIP 99577 is 1 mile from Eagle Rvr Gakona Circle, AK, which stands at 567 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 99577 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.