Basin weather by month
What a typical year looks like in Basin, Montana: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Boulder, 15 km from Basin; records cover 1880–2026.
The year at a glance
- Precipitation a year
- 10.8 in274 mm
- Snow a year
- Rare
- Last spring freeze
- Jun 11
- First fall freeze
- Sep 4
- Heating degree days
- 8,312
- Cooling degree days
- 156
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are −16°−27° (heating, 99%) and 93°34° (cooling, 1%).
Month by month
Basin in January
Highs average 35°2° and lows 12°−11°, with 0.28 in7.1 mm of precipitation in a typical January.
- Record high
- 59°15° (2026)
- Record low
- −38°−39° (1957)
- Heating degree days
- 1288
- Cooling degree days
- 0
Basin in February
Highs average 38°3° and lows 14°−10°, with 0.19 in4.8 mm of precipitation in a typical February.
- Record high
- 65°18° (1995)
- Record low
- −39° (1989)
- Heating degree days
- 1095
- Cooling degree days
- 0
Basin in March
Highs average 47°8° and lows 21°−6°, with 0.4 in10 mm of precipitation in a typical March.
- Record high
- 74°23° (2026)
- Record low
- −34°−37° (2019)
- Heating degree days
- 967
- Cooling degree days
- 0
Basin in April
Highs average 55°13° and lows 27°−3°, with 0.78 in20 mm of precipitation in a typical April.
- Record high
- 83°28° (1987)
- Record low
- −6°−21° (1997)
- Heating degree days
- 728
- Cooling degree days
- 0
Basin in May
Highs average 64°18° and lows 35°2°, with 1.9 in47 mm of precipitation in a typical May.
- Record high
- 89°32° (1950)
- Record low
- 9°−13° (1967)
- Heating degree days
- 482
- Cooling degree days
- 0
Basin in June
Highs average 72°22° and lows 43°6°, with 2.3 in58 mm of precipitation in a typical June.
- Record high
- 96°36° (1988)
- Record low
- 22°−6° (1954)
- Heating degree days
- 245
- Cooling degree days
- 12
Basin in July
Highs average 83°28° and lows 48°9°, with 1.4 in35 mm of precipitation in a typical July.
- Record high
- 101°38° (2002)
- Record low
- 29°−2° (1993)
- Heating degree days
- 68
- Cooling degree days
- 80
Basin in August
Highs average 82°28° and lows 46°8°, with 1.1 in28 mm of precipitation in a typical August.
- Record high
- 100°38° (1961)
- Record low
- 19°−7° (1992)
- Heating degree days
- 85
- Cooling degree days
- 57
Basin in September
Highs average 72°22° and lows 38°3°, with 1.1 in28 mm of precipitation in a typical September.
- Record high
- 96°36° (2022)
- Record low
- 8°−13° (1965)
- Heating degree days
- 307
- Cooling degree days
- 7
Basin in OctoberThis month
Highs average 57°14° and lows 28°−2°, with 0.64 in16 mm of precipitation in a typical October.
- Record high
- 87°31° (1992)
- Record low
- −14°−26° (1991)
- Heating degree days
- 696
- Cooling degree days
- 0
Basin in November
Highs average 42°6° and lows 19°−7°, with 0.48 in12 mm of precipitation in a typical November.
- Record high
- 71°22° (1999)
- Record low
- −34°−37° (1959)
- Heating degree days
- 1035
- Cooling degree days
- 0
Basin in December
Highs average 34°1° and lows 12°−11°, with 0.27 in6.9 mm of precipitation in a typical December.
- Record high
- 65°18° (2021)
- Record low
- −42°−41° (1990)
- Heating degree days
- 1316
- Cooling degree days
- 0