Frost Dates for 59425 — Conrad, Montana

Half of springs at Conrad, MT see their last 32°F night by May 20; only one in ten is past it by May 9, and one in ten still has one after June 3. Planting tender crops after May 26 leaves a 30% risk of a frost on them, after May 30 20%, and after June 3 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 60% of the 68 Montana stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 19 in half of years, as early as September 4 one year in ten, and holds off past October 2 one year in ten. A hard freeze of 28°F follows 11 days later, around September 30; in spring the one-in-ten date for 28°F is May 19, 15 days before the 32°F one. The freeze-free season lasts 119 days in a typical year, shorter than at 63% of the 68 Montana stations; it reaches 138 days one year in ten and falls short of 101 one year in ten. On average 188 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 June 7, and return around September 7. Severe cold of 16°F or below comes every winter, usually between October 27 and April 5.

July is the warmest month at Conrad, MT, averaging 82°F by day and 52°F at night; January is the coldest at 34°F and 11°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From July to August the chance of a 32°F night stays under 10% each month. In spring, June still brings one in 14% of years.

Warmth for growing adds up to 1,758 growing degree days a year (base 50°F), fewer than at 66% of the 68 Montana stations. 27% of them (466) have built up by the end of June, and July adds the most, 526. Precipitation totals 12.7 inches a year, most in June (2.6") and least in January (0.4"); May to September bring 62% of it.

The nearest other station, Shelby, MT, 23 miles north of Conrad and 225 feet lower, has a last frost 3 days later (May 23), a first frost 3 days earlier (September 16), a season 4 days shorter.

The first measurable snow (0.1 inch or more) in Conrad usually arrives around October 28, and the last of the season around April 13. Those are the middle dates across the winters of 1991–2020 at Conrad, MT, 1.4 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 37 days after the last snow.

ZIP 59425 is 1 mile from Conrad, MT, which stands at 3,550 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 59425 in zone 4a, the band where the coldest night of the year averaged -30 to -25°F (-34.4 to -31.7°C) over 1991–2020; a zone describes winter lows, not frost dates.