Frost Dates for 87544 — Los Alamos, New Mexico

Half of springs at Los Alamos, NM see their last 32°F night by May 2; only one in ten is past it by April 19, and one in ten still has one after May 17. Planting tender crops after May 9 leaves a 30% risk of a frost on them, after May 13 20%, and after May 17 10%. The 15 days between the even-odds date and the one-in-ten date is narrower than at 46% of the 70 New Mexico 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 October 1 one year in ten, and holds off past October 25 one year in ten. A hard freeze of 28°F follows 11 days later, around October 23; in spring the one-in-ten date for 28°F is May 4, 13 days before the 32°F one. The freeze-free season lasts 162 days in a typical year, shorter than at 56% of the 70 New Mexico stations; it reaches 180 days one year in ten and falls short of 141 one year in ten. On average 150 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 16, and return around October 4. Severe cold of 16°F or below comes every winter, usually between November 22 and March 3.

July is the warmest month at Los Alamos, NM, averaging 83°F by day and 57°F at night; January is the coldest at 40°F and 21°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 57% of years.

Warmth for growing adds up to 2,451 growing degree days a year (base 50°F), fewer than at 80% of the 70 New Mexico stations. 34% of them (844) have built up by the end of June, and July adds the most, 608. Precipitation totals 17.5 inches a year, most in August (3.2") and least in February (0.7"); May to September bring 60% of it.

The nearest other station, Cochiti Dam, NM, 16 miles south of Los Alamos and 1,864 feet lower, has a last frost 6 days earlier (April 26), a first frost 9 days later (October 21), a season 16 days longer.

The first measurable snow (0.1 inch or more) in Los Alamos usually arrives around November 5, and the last of the season around April 2. Those are the middle dates across the winters of 1991–2020 at Los Alamos, NM, 1.5 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 30 days after the last snow.

ZIP 87544 is 2 miles from Los Alamos, NM, which stands at 7,424 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 87544 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°C) over 1991–2020; a zone describes winter lows, not frost dates.