Sedan weather by month
What a typical year looks like in Sedan, Montana: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Wilsall 1s, 18 km from Sedan; records cover 2017–2026.
The year at a glance
- Precipitation a year
- 14.9 in378 mm
- Snow a year
- Rare
- Last spring freeze
- Rare
- First fall freeze
- Rare
- Heating degree days
- 8,697
- Cooling degree days
- 166
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are — (heating, 99%) and — (cooling, 1%).
Month by month
Sedan in January
Highs average 31°−1° and lows 11°−12°, with 0.51 in13 mm of precipitation in a typical January.
- Record high
- 64°18° (2026)
- Record low
- −36°−38° (2024)
- Heating degree days
- 1372
- Cooling degree days
- 0
Sedan in February
Highs average 36°2° and lows 14°−10°, with 0.56 in14 mm of precipitation in a typical February.
- Record high
- 63°17° (2020)
- Record low
- −35°−37° (2021)
- Heating degree days
- 1128
- Cooling degree days
- 0
Sedan in March
Highs average 43°6° and lows 21°−6°, with 1.1 in27 mm of precipitation in a typical March.
- Record high
- 78°26° (2026)
- Record low
- −16°−27° (2024)
- Heating degree days
- 1025
- Cooling degree days
- 0
Sedan in April
Highs average 52°11° and lows 26°−3°, with 1.8 in44 mm of precipitation in a typical April.
- Record high
- 78°26° (2018)
- Record low
- −2°−19° (2020)
- Heating degree days
- 774
- Cooling degree days
- 0
Sedan in May
Highs average 61°16° and lows 37°3°, with 2.3 in58 mm of precipitation in a typical May.
- Record high
- 84°29° (2026)
- Record low
- 8°−13° (2019)
- Heating degree days
- 496
- Cooling degree days
- 0
Sedan in June
Highs average 71°22° and lows 41°5°, with 2.4 in60 mm of precipitation in a typical June.
- Record high
- 92°33° (2021)
- Record low
- 25°−4° (2023)
- Heating degree days
- 267
- Cooling degree days
- 4
Sedan in July
Highs average 84°29° and lows 49°9°, with 1.4 in36 mm of precipitation in a typical July.
- Record high
- 103°39° (2026)
- Record low
- 31°−1° (2018)
- Heating degree days
- 48
- Cooling degree days
- 80
Sedan in August
Highs average 82°28° and lows 47°8°, with 1.1 in29 mm of precipitation in a typical August.
- Record high
- 103°39° (2026)
- Record low
- 27°−3° (2026)
- Heating degree days
- 86
- Cooling degree days
- 81
Sedan in September
Highs average 70°21° and lows 35°2°, with 1.3 in34 mm of precipitation in a typical September.
- Record high
- 95°35° (2022)
- Record low
- 18°−8° (2021)
- Heating degree days
- 370
- Cooling degree days
- 1
Sedan in OctoberThis month
Highs average 56°13° and lows 29°−2°, with 1.3 in33 mm of precipitation in a typical October.
- Record high
- 80°27° (2024)
- Record low
- −16°−27° (2019)
- Heating degree days
- 701
- Cooling degree days
- 0
Sedan in November
Highs average 42°6° and lows 15°−9°, with 0.74 in19 mm of precipitation in a typical November.
- Record high
- 70°21° (2024)
- Record low
- −12°−24° (2022)
- Heating degree days
- 1087
- Cooling degree days
- 0
Sedan in December
Highs average 34°1° and lows 10°−12°, with 0.48 in12 mm of precipitation in a typical December.
- Record high
- 65°18° (2021)
- Record low
- −38°−39° (2022)
- Heating degree days
- 1343
- Cooling degree days
- 0