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Frost dates / Montana / Billings

Frost dates in Billings, MT

The station on this page is BILLINGS LOGAN INTL AP, MT US (USW00024033), 1.4 miles from the city point. Population in the Census 2024 estimate is 121,483.

Zone 5aUSDA average annual extreme minimum -20°F to -15°F, from ZIP 59102 (1.7 miles from the city point used on this page).

Median last 32°F is May 4. Median first 32°F is October 7. The 50% growing-season length is 156 days. The green band runs from the median last frost to the median first frost. Thin ticks mark the 10%, 50%, and 90% dates.

Outside the median season Growing seasonTicks: 10%, 50%, and 90%

Last 32°F in spring

NCEI’s probability is the chance the last spring minimum of 32°F or lower occurs on or after the date.

ProbabilityDateHow to read it
90%April 20Earlier date. A last 32°F on or after this day is common.
50%May 4Median.
10%May 18Later date. A last 32°F on or after this day is uncommon.

First 32°F in fall

NCEI’s probability is the chance the first autumn minimum of 32°F or lower occurs on or before the date.

ProbabilityDateHow to read it
10%September 26Earlier date. A first 32°F on or before this day is uncommon.
50%October 7Median.
90%October 21Later date. A first 32°F on or before this day is common.

32°F growing-season length

Days between the last spring 32°F and the first autumn 32°F. The figure is a length the season meets or exceeds at that probability, from NCEI, not a subtraction done on this site.

Probability the season is at least this longDays
10%175
50%156
90%136

28°F threshold

10%50%90%
Last, on or afterMay 7April 21April 4
First, on or beforeOctober 1October 16October 31
Season at least200 days177 days156 days

36°F threshold

10%50%90%
Last, on or afterMay 29May 15May 2
First, on or beforeSeptember 16September 28October 12
Season at least153 days135 days116 days

Station BILLINGS LOGAN INTL AP, MT US (USW00024033). Completeness flag S, 30 years used for the 32°F dates. NCEI’s annual probability of at least one day at or below 32°F is 100%. Freeze dates are conditional on that threshold occurring. Elevation 1091.5 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.

Check a crop against this station

Billings, MT

Zone 5aAverage annual extreme minimum -20°F to -15°F

Median last 32°F is May 4. Median first 32°F is October 7. The 50% growing-season length is 156 days. The green band runs from the median last frost to the median first frost. Thin ticks mark the 10%, 50%, and 90% dates.

Outside the median season Growing seasonTicks: 10%, 50%, and 90%

Montana. Nearest qualified station: BILLINGS LOGAN INTL AP, MT US (USW00024033), 1.4 miles. Median last 32°F May 4. Median first 32°F October 7. The 50% growing-season length is 156 days.

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32°F probabilities at this station
10%50%90%
Last 32°F on or afterMay 18May 4April 20
First 32°F on or beforeSeptember 26October 7October 21

Column order matches the NCEI file: for the last freeze, 10% is the later date and 90% is the earlier date. How to read the probabilities.

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Planting calendar

Frost dates for Montana are above. Planting windows appear for states with a cited extension guide. The fall and seed tools use the numbers you enter and the station dates.

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