Unionville weather by month
What a typical year looks like in Unionville, Montana: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Helena Airport Asos, 10 km from Unionville; records cover 1880–2026.
The year at a glance
- Precipitation a year
- 11.4 in290 mm
- Snow a year
- 37 in94 cm
- Last spring freeze
- May 10
- First fall freeze
- Sep 27
- Heating degree days
- 7,500
- Cooling degree days
- 433
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are −13°−25° (heating, 99%) and 97°36° (cooling, 1%).
Month by month
Unionville in January
Highs average 32°0° and lows 14°−10°, with 0.39 in9.9 mm of precipitation and 7 in17 cm of snow in a typical January.
- Record high
- 63°17° (1902)
- Record low
- −42°−41° (1893)
- Heating degree days
- 1304
- Cooling degree days
- 0
Unionville in February
Highs average 37°3° and lows 17°−8°, with 0.42 in11 mm of precipitation and 7 in17 cm of snow in a typical February.
- Record high
- 69°21° (1932)
- Record low
- −42°−41° (1996)
- Heating degree days
- 1058
- Cooling degree days
- 0
Unionville in March
Highs average 48°9° and lows 25°−4°, with 0.52 in13 mm of precipitation and 5 in12 cm of snow in a typical March.
- Record high
- 78°26° (2004)
- Record low
- −30°−34° (1955)
- Heating degree days
- 898
- Cooling degree days
- 0
Unionville in April
Highs average 57°14° and lows 32°0°, with 1 in26 mm of precipitation and 2.9 in7.4 cm of snow in a typical April.
- Record high
- 86°30° (1910)
- Record low
- −10°−23° (1936)
- Heating degree days
- 614
- Cooling degree days
- 0
Unionville in May
Highs average 66°19° and lows 42°5°, with 2 in50 mm of precipitation and 0.1 in0.3 cm of snow in a typical May.
- Record high
- 95°35° (1919)
- Record low
- 17°−8° (1954)
- Heating degree days
- 350
- Cooling degree days
- 7
Unionville in June
Highs average 75°24° and lows 49°9°, with 2.2 in56 mm of precipitation in a typical June.
- Record high
- 104°40° (2021)
- Record low
- 30°−1° (1969)
- Heating degree days
- 144
- Cooling degree days
- 45
Unionville in July
Highs average 86°30° and lows 55°13°, with 1.1 in27 mm of precipitation in a typical July.
- Record high
- 105°41° (2002)
- Record low
- 36°2° (1898)
- Heating degree days
- 23
- Cooling degree days
- 197
Unionville in August
Highs average 85°29° and lows 53°12°, with 1 in26 mm of precipitation and 0.3 in0.8 cm of snow in a typical August.
- Record high
- 105°41° (1969)
- Record low
- 28°−2° (1992)
- Heating degree days
- 40
- Cooling degree days
- 156
Unionville in September
Highs average 73°23° and lows 45°7°, with 0.96 in24 mm of precipitation and 0.2 in0.5 cm of snow in a typical September.
- Record high
- 102°39° (2022)
- Record low
- 6°−14° (1926)
- Heating degree days
- 210
- Cooling degree days
- 28
Unionville in OctoberThis month
Highs average 58°14° and lows 34°1°, with 0.78 in20 mm of precipitation and 2.8 in7.1 cm of snow in a typical October.
- Record high
- 89°32° (2024)
- Record low
- −8°−22° (1935)
- Heating degree days
- 603
- Cooling degree days
- 0
Unionville in November
Highs average 43°6° and lows 23°−5°, with 0.59 in15 mm of precipitation and 5 in14 cm of snow in a typical November.
- Record high
- 76°24° (2020)
- Record low
- −39° (1959)
- Heating degree days
- 966
- Cooling degree days
- 0
Unionville in December
Highs average 33°0° and lows 14°−10°, with 0.46 in12 mm of precipitation and 8 in20 cm of snow in a typical December.
- Record high
- 70°21° (2021)
- Record low
- −40° (1880)
- Heating degree days
- 1290
- Cooling degree days
- 0