Fallon weather by month
What a typical year looks like in Fallon, Montana: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Terry, 14 km from Fallon; records cover 1949–2026.
The year at a glance
- Precipitation a year
- 13.4 in339 mm
- Snow a year
- 12 in30 cm
- Last spring freeze
- May 15
- First fall freeze
- Sep 22
- Heating degree days
- 7,827
- Cooling degree days
- 673
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are −22°−30° (heating, 99%) and 101°38° (cooling, 1%).
Month by month
Fallon in January
Highs average 28°−2° and lows 6°−14°, with 0.29 in7.4 mm of precipitation and 3 in8 cm of snow in a typical January.
- Record high
- 65°18° (2002)
- Record low
- −45°−43° (1954)
- Heating degree days
- 1480
- Cooling degree days
- 0
Fallon in February
Highs average 34°1° and lows 11°−12°, with 0.34 in8.6 mm of precipitation and 1.4 in3.6 cm of snow in a typical February.
- Record high
- 73°23° (1992)
- Record low
- −41° (1982)
- Heating degree days
- 1197
- Cooling degree days
- 0
Fallon in March
Highs average 46°8° and lows 22°−6°, with 0.44 in11 mm of precipitation and 1.2 in3 cm of snow in a typical March.
- Record high
- 83°28° (2015)
- Record low
- −35°−37° (1962)
- Heating degree days
- 966
- Cooling degree days
- 0
Fallon in April
Highs average 58°14° and lows 32°0°, with 1.4 in36 mm of precipitation and 1 in2.5 cm of snow in a typical April.
- Record high
- 93°34° (1952)
- Record low
- −5°−21° (1986)
- Heating degree days
- 599
- Cooling degree days
- 1
Fallon in May
Highs average 68°20° and lows 43°6°, with 2.5 in64 mm of precipitation in a typical May.
- Record high
- 102°39° (1988)
- Record low
- 11°−12° (1984)
- Heating degree days
- 316
- Cooling degree days
- 17
Fallon in June
Highs average 78°26° and lows 53°11°, with 2.4 in60 mm of precipitation in a typical June.
- Record high
- 110°43° (1988)
- Record low
- 27°−3° (1985)
- Heating degree days
- 84
- Cooling degree days
- 96
Fallon in July
Highs average 88°31° and lows 59°15°, with 1.9 in48 mm of precipitation in a typical July.
- Record high
- 113°45° (2026)
- Record low
- 34°1° (1985)
- Heating degree days
- 13
- Cooling degree days
- 270
Fallon in August
Highs average 87°31° and lows 56°13°, with 1.3 in33 mm of precipitation in a typical August.
- Record high
- 111°44° (1995)
- Record low
- 28°−2° (1988)
- Heating degree days
- 30
- Cooling degree days
- 232
Fallon in September
Highs average 76°24° and lows 45°7°, with 1.2 in30 mm of precipitation in a typical September.
- Record high
- 106°41° (1983)
- Record low
- 15°−9° (1989)
- Heating degree days
- 189
- Cooling degree days
- 54
Fallon in OctoberThis month
Highs average 59°15° and lows 33°0°, with 0.92 in23 mm of precipitation and 0.2 in0.5 cm of snow in a typical October.
- Record high
- 94°34° (1953)
- Record low
- −9°−23° (1991)
- Heating degree days
- 595
- Cooling degree days
- 3
Fallon in November
Highs average 44°7° and lows 20°−7°, with 0.37 in9.4 mm of precipitation and 1.6 in4.1 cm of snow in a typical November.
- Record high
- 79°26° (1987)
- Record low
- −31°−35° (1985)
- Heating degree days
- 993
- Cooling degree days
- 0
Fallon in December
Highs average 32°0° and lows 10°−12°, with 0.32 in8.1 mm of precipitation and 3 in8 cm of snow in a typical December.
- Record high
- 72°22° (2021)
- Record low
- −47°−44° (1989)
- Heating degree days
- 1365
- Cooling degree days
- 0