Boneau weather by month
What a typical year looks like in Boneau, Montana: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Fort Assiniboine, 23 km from Boneau; records cover 1917–2026.
The year at a glance
- Precipitation a year
- 13.1 in334 mm
- Snow a year
- 35 in88 cm
- Last spring freeze
- May 13
- First fall freeze
- Sep 25
- Heating degree days
- 8,198
- Cooling degree days
- 395
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are −23°−31° (heating, 99%) and 98°37° (cooling, 1%).
Month by month
Boneau in January
Highs average 28°−2° and lows 7°−14°, with 0.42 in11 mm of precipitation and 6 in16 cm of snow in a typical January.
- Record high
- 68°20° (1992)
- Record low
- −49°−45° (1969)
- Heating degree days
- 1465
- Cooling degree days
- 0
Boneau in February
Highs average 33°0° and lows 10°−12°, with 0.34 in8.6 mm of precipitation and 7 in19 cm of snow in a typical February.
- Record high
- 75°24° (1992)
- Record low
- −48°−44° (1936)
- Heating degree days
- 1219
- Cooling degree days
- 0
Boneau in March
Highs average 44°7° and lows 19°−7°, with 0.47 in12 mm of precipitation and 4 in10 cm of snow in a typical March.
- Record high
- 82°28° (2004)
- Record low
- −34°−37° (1947)
- Heating degree days
- 1032
- Cooling degree days
- 0
Boneau in April
Highs average 57°14° and lows 31°−1°, with 1.2 in30 mm of precipitation and 2.7 in6.9 cm of snow in a typical April.
- Record high
- 94°34° (1939)
- Record low
- −11°−24° (1975)
- Heating degree days
- 638
- Cooling degree days
- 0
Boneau in May
Highs average 67°19° and lows 40°5°, with 2.1 in54 mm of precipitation and 0.7 in1.8 cm of snow in a typical May.
- Record high
- 98°37° (1936)
- Record low
- 11°−12° (1954)
- Heating degree days
- 361
- Cooling degree days
- 8
Boneau in June
Highs average 75°24° and lows 49°9°, with 2.9 in74 mm of precipitation in a typical June.
- Record high
- 108°42° (1984)
- Record low
- 30°−1° (1969)
- Heating degree days
- 138
- Cooling degree days
- 40
Boneau in July
Highs average 85°30° and lows 54°12°, with 1.7 in42 mm of precipitation in a typical July.
- Record high
- 107°42° (2007)
- Record low
- 37°3° (1952)
- Heating degree days
- 30
- Cooling degree days
- 169
Boneau in August
Highs average 84°29° and lows 52°11°, with 0.96 in24 mm of precipitation in a typical August.
- Record high
- 111°44° (1961)
- Record low
- 30°−1° (1981)
- Heating degree days
- 51
- Cooling degree days
- 151
Boneau in September
Highs average 73°23° and lows 43°6°, with 1.2 in30 mm of precipitation in a typical September.
- Record high
- 102°39° (1967)
- Record low
- 12°−11° (1944)
- Heating degree days
- 239
- Cooling degree days
- 26
Boneau in OctoberThis month
Highs average 58°14° and lows 31°−1°, with 0.89 in23 mm of precipitation and 1.9 in4.8 cm of snow in a typical October.
- Record high
- 91°33° (1963)
- Record low
- −21°−29° (1991)
- Heating degree days
- 646
- Cooling degree days
- 1
Boneau in November
Highs average 42°6° and lows 20°−7°, with 0.62 in16 mm of precipitation and 5 in13 cm of snow in a typical November.
- Record high
- 78°26° (1975)
- Record low
- −28°−33° (1985)
- Heating degree days
- 1018
- Cooling degree days
- 0
Boneau in December
Highs average 32°0° and lows 11°−12°, with 0.36 in9.1 mm of precipitation and 6 in16 cm of snow in a typical December.
- Record high
- 69°21° (1939)
- Record low
- −44°−42° (1968)
- Heating degree days
- 1361
- Cooling degree days
- 0