Frost Dates for 99686 — Valdez, Alaska

Half of springs at Valdez WSO, AK see their last 32°F night by April 30; only one in ten is past it by April 17, and one in ten still has one after May 10. Planting tender crops after May 3 leaves a 30% risk of a frost on them, after May 6 20%, and after May 10 10%. The 10 days between the even-odds date and the one-in-ten date is narrower than at 89% of the 37 Alaska stations behind this site's ZIP pages, so the end of frost is fairly predictable.

In fall the first 32°F night comes by October 2 in half of years, as early as September 20 one year in ten, and holds off past October 19 one year in ten. A hard freeze of 28°F follows 18 days later, around October 20; in spring the one-in-ten date for 28°F is April 26, 14 days before the 32°F one. The freeze-free season lasts 157 days in a typical year, longer than at 78% of the 37 Alaska stations; it reaches 177 days one year in ten and falls short of 138 one year in ten. On average 174 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 15, and return around September 20. Severe cold of 16°F or below comes every winter, usually between November 21 and March 18.

July is the warmest month at Valdez WSO, AK, averaging 64°F by day and 49°F at night; January is the coldest at 29°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 46% of years.

Warmth for growing adds up to 537 growing degree days a year (base 50°F), fewer than at 73% of the 37 Alaska stations. 31% of them (168) have built up by the end of June, and July adds the most, 205. Precipitation totals 67.9 inches a year, most in September (9.8") and least in June (2.4"); May to September bring 38% of it.

The first measurable snow (0.1 inch or more) in Valdez usually arrives around October 14, and the last of the season around April 23. Those are the middle dates across the winters of 1991–2020 at Valdez WSO, AK, 3.9 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 7 days after the last snow.

ZIP 99686 is 4 miles from Valdez WSO, AK, which stands at 95 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 99686 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.