Grant weather by month
What a typical year looks like in Grant, Montana: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Dillon 18 Wsw, 17 km from Grant; records cover 2007–2026.
The year at a glance
- Precipitation a year
- 10.1 in256 mm
- Snow a year
- Rare
- Last spring freeze
- Jun 17
- First fall freeze
- Aug 25
- Heating degree days
- 9,590
- Cooling degree days
- 35
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are −21°−30° (heating, 99%) and 90°32° (cooling, 1%).
Month by month
Grant in January
Highs average 28°−2° and lows 8°−13°, with 0.34 in8.6 mm of precipitation in a typical January.
- Record high
- 54°12° (2026)
- Record low
- −37°−38° (2017)
- Heating degree days
- 1459
- Cooling degree days
- 0
Grant in February
Highs average 32°0° and lows 9°−13°, with 0.56 in14 mm of precipitation in a typical February.
- Record high
- 57°14° (2015)
- Record low
- −42°−41° (2014)
- Heating degree days
- 1247
- Cooling degree days
- 0
Grant in March
Highs average 41°5° and lows 18°−8°, with 0.56 in14 mm of precipitation in a typical March.
- Record high
- 72°22° (2026)
- Record low
- −25°−32° (2019)
- Heating degree days
- 1104
- Cooling degree days
- 0
Grant in April
Highs average 50°10° and lows 26°−4°, with 1 in25 mm of precipitation in a typical April.
- Record high
- 78°26° (2021)
- Record low
- −3°−19° (2022)
- Heating degree days
- 814
- Cooling degree days
- 0
Grant in May
Highs average 60°16° and lows 33°1°, with 1.6 in40 mm of precipitation in a typical May.
- Record high
- 86°30° (2020)
- Record low
- 8°−13° (2019)
- Heating degree days
- 564
- Cooling degree days
- 0
Grant in June
Highs average 69°21° and lows 39°4°, with 1.8 in47 mm of precipitation in a typical June.
- Record high
- 92°33° (2015)
- Record low
- 23°−5° (2021)
- Heating degree days
- 332
- Cooling degree days
- 2
Grant in July
Highs average 81°27° and lows 44°7°, with 0.62 in16 mm of precipitation in a typical July.
- Record high
- 98°37° (2026)
- Record low
- 29°−2° (2018)
- Heating degree days
- 100
- Cooling degree days
- 21
Grant in August
Highs average 79°26° and lows 42°6°, with 0.69 in18 mm of precipitation in a typical August.
- Record high
- 95°35° (2018)
- Record low
- 29°−2° (2012)
- Heating degree days
- 149
- Cooling degree days
- 12
Grant in September
Highs average 69°20° and lows 35°2°, with 0.85 in22 mm of precipitation in a typical September.
- Record high
- 96°36° (2022)
- Record low
- 16°−9° (2014)
- Heating degree days
- 398
- Cooling degree days
- 0
Grant in OctoberThis month
Highs average 53°12° and lows 25°−4°, with 0.86 in22 mm of precipitation in a typical October.
- Record high
- 82°28° (2010)
- Record low
- −13°−25° (2019)
- Heating degree days
- 795
- Cooling degree days
- 0
Grant in November
Highs average 39°4° and lows 15°−10°, with 0.47 in12 mm of precipitation in a typical November.
- Record high
- 69°21° (2020)
- Record low
- −23°−31° (2014)
- Heating degree days
- 1154
- Cooling degree days
- 0
Grant in December
Highs average 28°−2° and lows 7°−14°, with 0.71 in18 mm of precipitation in a typical December.
- Record high
- 59°15° (2021)
- Record low
- −40° (2022)
- Heating degree days
- 1474
- Cooling degree days
- 0