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When does it first snow in Mason City, IA?

At Mason City, the typical date of the first measurable snowfall (0.1 inch or more in a day) is Nov 10. 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 14, and in 1 in 10 not until Dec 3 or later. The earliest was Oct 1 (1999-00) and the latest Dec 9 (2012-13). A first snowfall of at least 1 inch in a single day typically arrives around Nov 30, and 100% of seasons had one. The first freeze of fall (a low of 32°F or colder) typically comes around Sep 30, and the last freeze of spring around May 3.

This season so far (2026-27, data through Oct 16, 2026): no measurable snow recorded yet; no 32°F freeze recorded yet 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.

Nov 10Median first measurable snow (0.1"+)

Nov 30Median first 1"+ snowfall

42.1"Average snowfall per season

54%Chance of white Christmas (1"+ on ground Dec 25)

Sep 30Median first fall freeze (≤32°F)

May 3Median last spring freeze (≤32°F)

152Median freeze-free days between

First snowfall dates at Mason City

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)	Nov 10	Oct 14 – Dec 3	Oct 1 (1999-00)	Dec 9 (2012-13)	100%
1" of snow or more	Nov 30	Nov 5 – Dec 20	Oct 24 (2002-03)	Jan 9 (2023-24)	100%
3" of snow or more	Dec 20	Nov 25 – Feb 1	Nov 10 (2006-07)	Mar 5 (2017-18)	100%

Based on 28 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)	32%	82%	100%
1"+	7%	54%	96%

In spring, the last measurable snowfall of the season typically falls around Apr 7 (median).

White Christmas odds in Mason City

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, Mason City had that in 54% of years, at least 3 inches in 39%, and at least 6 inches in 21%. The average depth on Dec 25 was 3.4 inches and the deepest was 18 inches. New snow was falling (0.1" or more) on Christmas Day itself in 21% of years. Based on 28 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 Feb 9 (88%). Red line: Dec 25.

First and last freeze dates in Mason City

Threshold	Event	Median date	Typical range (10th–90th pct)	Earliest / latest	Years with one
32°F or colder (freeze)	First in fall	Sep 30	Sep 20 – Oct 14	Sep 13 (2014) / Oct 21 (2021)	100%
32°F or colder (freeze)	Last in spring	May 3	Apr 22 – May 17	–	100%
28°F or colder (hard freeze)	First in fall	Oct 11	Sep 28 – Oct 22	Sep 15 (2007) / Oct 28 (2023)	100%
28°F or colder (hard freeze)	Last in spring	Apr 25	Apr 10 – May 5	–	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 152 days.

Nearby weather stations

Source station: Mason City Muni Ap (USW00014940), elevation 1,188 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 Iowa (on our sister site PlugVsPump, from EIA prices).