Great Falls, MT

Montana · Records since 1891–2026

🌤️ 54°F
Currently in Great Falls
As of 12:30 PM MDT

Records for September 11

🔥 Record High

93°F

September 11, 1919

+19° from 74° normal

❄ Record Low

29°F

September 11, 1989

-15° from 44° normal
🌞 Normal high: 74°F 🌑 Normal low: 44°F 1991–2020 normals

All-Time Records — Great Falls

🔥
107°F
Hottest Day Ever
Jul 25, 1933
❄
-49°F
Coldest Day Ever
Feb 15, 1936
🌧
3.36"
Wettest Day Ever
Jun 23, 1907
☃
16.5"
Most Snow in One Day
Apr 20, 1973

First & Last Dates — Great Falls

How early and how late each seasonal turning point has ever arrived, across the full period of record

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Range ever recorded Normal date (1991–2020)
184 days
Longest growing season
1940
91 days
Shortest growing season
1992
123 days
Normal growing season
1991–2020 average

Top 10 Record Highs — September 11

# Temp Date
🏆 93°F September 11, 1919
2 91°F September 11, 2011
3 90°F September 11, 2017
4 90°F September 11, 1981
5 90°F September 11, 1969
6 90°F September 11, 1958
7 88°F September 11, 2022
8 88°F September 11, 1990
9 88°F September 11, 1968
10 88°F September 11, 1940

Top 5 Record Lows — September 11

# Temp Date
🥶 29°F September 11, 1989
2 29°F September 11, 1921
3 31°F September 11, 1970
4 31°F September 11, 1949
5 32°F September 11, 2014
About this data — Records are sourced from the NOAA Threadex dataset via RCC ACIS, a quality-controlled record for long-term climate stations. Threadex adjusts for station relocations and observation-time changes, making records comparable across all years since 1891–2026. Climate normals represent the 1991–2020 average.

Heat Wave Summary — Great Falls

threshold: 93°F (90th percentile of historical Jun–Aug highs)
4.3
Avg heat wave length
days (historical)
99°
Avg peak temp
during heat waves
0
Dangerous nights 2026
Overnights ≥ 70°F
2
Heat waves 2026
so far

Days ≥ 90°F Per Year

1892–2026
23
2026 so far
20
Avg/year 1970–2025
27
Avg/year (last 10 complete)
50
Most in a year (1919)

Average Daily High by Decade

Full year · complete decades only

Longest Heat Waves — Great Falls

# Dates Days Peak Avg High Avg Overnight Low
🏆 Jul 13, 2007 – Jul 23, 2007 11 104°F (Jul 15) 98°F 64°F
2 Jun 30, 1985 – Jul 10, 1985 11 101°F (Jul 5) 98°F 60°F
3 Jul 14, 1960 – Jul 23, 1960 10 102°F (Jul 22) 96°F 64°F
4 Aug 1, 1971 – Aug 9, 1971 9 101°F (Aug 5) 98°F 64°F
5 Jul 16, 1917 – Jul 24, 1917 9 100°F (Jul 22) 96°F 57°F
6 Jul 20, 1931 – Jul 27, 1931 8 103°F (Jul 21) 100°F 59°F
7 Jul 17, 1936 – Jul 24, 1936 8 102°F (Jul 17) 98°F 65°F
8 Jul 28, 2022 – Aug 4, 2022 8 101°F (Aug 1) 96°F 58°F
9 Jul 9, 1939 – Jul 16, 1939 8 100°F (Jul 10) 96°F 60°F
10 Jul 22, 2006 – Jul 29, 2006 8 100°F (Jul 28) 97°F 59°F

Heat Waves Per Year

Warm Summer Nights (Jun–Aug)

Nights where the overnight low exceeded the 1991–2020 normal low

54
2026 total
above-normal nights
50.7
Avg / summer
1970–2020
82
Most in a summer
1961

Above-Normal Summer Nights Per Year

Average June–August Low by Decade

Overnight lows · complete decades only

Precipitation

Annual totals and trend across the full period of record · see this year's standing →

Monthly Precipitation — Last 24 Months

Blue = actual · dashed line = monthly normal

Annual Precipitation Per Year (1891–2026)

Blue = above average · tan = below average · gold = 2026 (partial)
Since 1891, annual totals have trended +0.03" per decade, about +0.4" across the record.

Heavy Rain Days Per Year (≥ 1.0")

Compare year-to-year changes in days with heavy rainfall (≥ 1.0")

This Year — 2026

How Great Falls is tracking against normal, year to date

Daily High Temperature vs Normal

Above normal Below normal

159 of 253 days with data were above the 1991–2020 normal high for their date.

Precipitation, Year to Date

14.47"
2026 YTD
Normal: 11.62"
+2.85"
0.51"
September so far
September normal: 1.33"
-0.82"
4
2026 heavy rain days
Days with ≥ 1.0"

Accumulation vs. Normal

Running total since Jan 1 against the normal pace for the same date · Great Falls is 2.85" ahead of the normal pace

Period Review — Sep 3 – Sep 10, 2026

Any window, evaluated against every other year on record — 8 days

Quick picks: Last 7 days Last 30 days Last 90 days This month
Seasons: Spring (Mar–May) Summer (Jun–Aug) Fall (Sep–Nov)
60.6°F
Average temperature
61st-coolest of 132
+0.1°
vs. average
Normal: 60.4°F (1991–2020)

Average Temperature by Year — Sep 3 – Sep 10

1894–2026 · 2026 highlighted · trend +0.21° per decade (warming since 1894)

Precipitation by Year — Sep 3 – Sep 10

1892–2025 · 2026 highlighted · trend -0.01" per decade (drier since 1892)

Warmest Sep 3 – Sep 10 on Record

# Year Avg Temp
1 1998 71.4°F
2 1966 71.0°F
3 1963 70.5°F
4 2013 69.7°F
5 1967 69.6°F
6 1978 69.0°F
7 1990 68.2°F
8 1908 67.8°F
9 2006 67.6°F
10 1931 67.3°F

Coolest Sep 3 – Sep 10 on Record

# Year Avg Temp
1 1965 48.6°F
2 1929 48.8°F
3 1964 49.2°F
4 1989 49.9°F
5 1985 50.0°F
6 1901 50.5°F
7 1921 51.0°F
8 1911 51.7°F
9 2008 51.7°F
10 1898 52.0°F
About this data. Pick any start and end date and this becomes the same kind of review as the Month and Fall tabs, just for exactly the window you asked for — the generalized version of the same engine, evaluated across every year on record. Average temperature is the mean of each day's (high + low) / 2; precipitation is the sum of daily totals. A year missing more than about a fifth of the window's days is excluded from the temperature ranking; any missing day excludes a year from the precipitation ranking, since an unreported day is unreported rain. Ranges that cross from December into January aren't supported yet. Normals are the 1991–2020 mean for the same window.
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