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When does it first snow in Glasgow, MT?

At Glasgow, the typical date of the first measurable snowfall (0.1 inch or more in a day) is Oct 23. That is the median over the last 30 snow seasons: half of seasons saw it earlier, half later. In about 1 season in 10 it came by Oct 5, and in 1 in 10 not until Nov 21 or later. The earliest was Oct 2 (1999-00) and the latest Dec 4 (2021-22). A first snowfall of at least 1 inch in a single day typically arrives around Nov 8, and 100% of seasons had one. The first freeze of fall (a low of 32°F or colder) typically comes around Sep 28, and the last freeze of spring around May 13.

This season so far (2026-27, data through Oct 16, 2026): no measurable snow recorded yet; first freeze (32°F or colder) Oct 14 at this station. Compare with the typical dates above. This is observed data and can lag by a day or two, and it is not a forecast.

Oct 23Median first measurable snow (0.1"+)

Nov 8Median first 1"+ snowfall

41.3"Average snowfall per season

60%Chance of white Christmas (1"+ on ground Dec 25)

Sep 28Median first fall freeze (≤32°F)

May 13Median last spring freeze (≤32°F)

138Median freeze-free days between

First snowfall dates at Glasgow

First day with…	Median date	Typical range (10th–90th pct)	Earliest in 30 seasons	Latest in 30 seasons	Seasons with one
0.1" of snow or more (measurable)	Oct 23	Oct 5 – Nov 21	Oct 2 (1999-00)	Dec 4 (2021-22)	100%
1" of snow or more	Nov 8	Oct 14 – Dec 11	Oct 3 (2018-19)	Jan 17 (2007-08)	100%
3" of snow or more	Dec 7	Nov 2 – Feb 12	Oct 12 (2008-09)	Mar 23 (1997-98)	93%

Based on 30 seasons (July–June, 1995-96 to 2024-25) with at least 85% complete daily snowfall records at the station. Dates are for a single day’s snowfall, so "1 inch" means one calendar day with 1" or more, not total accumulation.

Chance the first snow has already happened by a given date

Snowfall	By Nov 1	By Dec 1	By Jan 1
0.1"+ (measurable)	70%	97%	100%
1"+	37%	77%	97%

In spring, the last measurable snowfall of the season typically falls around Apr 17 (median).

White Christmas odds in Glasgow

NOAA defines a white Christmas as at least 1 inch of snow on the ground on the morning of December 25. Using the last 30 years of daily snow-depth records (1995–2024) at this station, Glasgow had that in 60% of years, at least 3 inches in 37%, and at least 6 inches in 10%. The average depth on Dec 25 was 2.4 inches and the deepest was 11 inches. New snow was falling (0.1" or more) on Christmas Day itself in 23% of years. Based on 30 years with a recorded depth on Dec 25.

Chance of at least 1 inch of snow on the ground, by date

Share of the last 30 years with 1"+ snow depth within 3 days of each date. Snow cover is most likely around Jan 19 (82%). Red line: Dec 25.

First and last freeze dates in Glasgow

Threshold	Event	Median date	Typical range (10th–90th pct)	Earliest / latest	Years with one
32°F or colder (freeze)	First in fall	Sep 28	Sep 14 – Oct 13	Sep 8 (2020) / Oct 15 (2015)	100%
32°F or colder (freeze)	Last in spring	May 13	May 2 – May 22	–	100%
28°F or colder (hard freeze)	First in fall	Oct 6	Sep 28 – Oct 22	Sep 13 (2016) / Oct 30 (2024)	100%
28°F or colder (hard freeze)	Last in spring	Apr 29	Apr 17 – May 14	–	100%

Based on the station’s daily minimum temperature, 1995–2024. “Freeze” here means a daily low at or below the threshold, which is not the same as visible frost. Your yard can differ by several degrees and days from an airport weather station, so use these as planning odds, not guarantees.

The median stretch between the last spring freeze and the first fall freeze (the freeze-free season) was about 138 days.

Nearby weather stations

Source station: Glasgow (USW00094008), elevation 2,384 ft. Data: NOAA NCEI GHCN-Daily. Computed by First Snow Dates; how we calculate this. Historical averages only; for a forecast see weather.gov.

Planning for winter? Heat pump vs gas furnace, propane and oil: heating cost in Montana (on our sister site PlugVsPump, from EIA prices).