Frost Dates for 99603 — Homer, Alaska

Half of springs at Homer Airport, AK see their last 32°F night by May 10; only one in ten is past it by April 27, and one in ten still has one after May 23. Planting tender crops after May 16 leaves a 30% risk of a frost on them, after May 19 20%, and after May 23 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 29 in half of years, as early as September 14 one year in ten, and holds off past October 13 one year in ten. A hard freeze of 28°F follows 12 days later, around October 11; in spring the one-in-ten date for 28°F is May 7, 16 days before the 32°F one. The freeze-free season lasts 141 days in a typical year, longer than at 62% of the 37 Alaska stations; it reaches 160 days one year in ten and falls short of 121 one year in ten. On average 169 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 18 days longer, to about May 28, and return around September 16. Severe cold of 16°F or below comes every winter, usually between November 13 and March 24.

July is the warmest month at Homer Airport, AK, averaging 63°F by day and 49°F at night; January is the coldest at 32°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 77% of years.

Warmth for growing adds up to 501 growing degree days a year (base 50°F), fewer than at 76% of the 37 Alaska stations. 18% of them (93) have built up by the end of June, and July adds the most, 192. Precipitation totals 24.1 inches a year, most in September (3.3") and least in May (0.8"); May to September bring 37% of it.

The nearest other station, Homer 8 NW, AK, 8 miles northwest of Homer and 1,016 feet higher, has a last frost 6 days later (May 16), a first frost 1 day later (September 30), a season 5 days shorter.

The first measurable snow (0.1 inch or more) in Homer usually arrives around October 22, and the last of the season around April 15. Those are the middle dates across the winters of 1991–2020 at Homer 9 E, AK, 5.6 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 25 days after the last snow.

ZIP 99603 is 2 miles from Homer Airport, AK, which stands at 64 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 99603 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.