Mammoth weather by month
What a typical year looks like in Mammoth, Wyoming: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Yellowstone Park Mammoth, 1 km from Mammoth; records cover 1894–2026.
The year at a glance
- Precipitation a year
- 14.8 in376 mm
- Snow a year
- 72 in182 cm
- Last spring freeze
- Jun 7
- First fall freeze
- Sep 16
- Heating degree days
- 8,924
- Cooling degree days
- 126
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are −11°−24° (heating, 99%) and 90°32° (cooling, 1%).
Month by month
Mammoth in January
Highs average 31°0° and lows 12°−11°, with 0.91 in23 mm of precipitation and 12 in29 cm of snow in a typical January.
- Record high
- 55°13° (2024)
- Record low
- −36°−38° (1951)
- Heating degree days
- 1344
- Cooling degree days
- 0
Mammoth in February
Highs average 34°1° and lows 12°−11°, with 0.79 in20 mm of precipitation and 12 in29 cm of snow in a typical February.
- Record high
- 56°13° (1995)
- Record low
- −35°−37° (1899)
- Heating degree days
- 1169
- Cooling degree days
- 0
Mammoth in March
Highs average 42°5° and lows 19°−7°, with 1.1 in28 mm of precipitation and 11 in28 cm of snow in a typical March.
- Record high
- 68°20° (2026)
- Record low
- −25°−32° (1956)
- Heating degree days
- 1070
- Cooling degree days
- 0
Mammoth in April
Highs average 50°10° and lows 26°−3°, with 1.4 in36 mm of precipitation and 8 in20 cm of snow in a typical April.
- Record high
- 78°26° (1987)
- Record low
- −6°−21° (2008)
- Heating degree days
- 810
- Cooling degree days
- 0
Mammoth in May
Highs average 60°15° and lows 35°1°, with 1.8 in46 mm of precipitation and 1.7 in4.3 cm of snow in a typical May.
- Record high
- 86°30° (2003)
- Record low
- 6°−14° (1950)
- Heating degree days
- 555
- Cooling degree days
- 0
Mammoth in June
Highs average 70°21° and lows 42°6°, with 1.9 in47 mm of precipitation and 0.3 in0.8 cm of snow in a typical June.
- Record high
- 92°33° (1900)
- Record low
- 20°−7° (1901)
- Heating degree days
- 287
- Cooling degree days
- 9
Mammoth in July
Highs average 81°27° and lows 48°9°, with 1.3 in32 mm of precipitation in a typical July.
- Record high
- 99°37° (2002)
- Record low
- 21°−6° (1976)
- Heating degree days
- 80
- Cooling degree days
- 66
Mammoth in August
Highs average 80°27° and lows 47°8°, with 1.1 in27 mm of precipitation in a typical August.
- Record high
- 97°36° (2003)
- Record low
- 24°−4° (1968)
- Heating degree days
- 103
- Cooling degree days
- 46
Mammoth in September
Highs average 69°20° and lows 39°4°, with 1.2 in31 mm of precipitation and 0.6 in1.5 cm of snow in a typical September.
- Record high
- 94°34° (2022)
- Record low
- 0°−18° (1895)
- Heating degree days
- 338
- Cooling degree days
- 5
Mammoth in OctoberThis month
Highs average 54°12° and lows 29°−2°, with 1.3 in34 mm of precipitation and 5 in12 cm of snow in a typical October.
- Record high
- 81°27° (2010)
- Record low
- −8°−22° (1991)
- Heating degree days
- 736
- Cooling degree days
- 0
Mammoth in November
Highs average 39°4° and lows 19°−7°, with 1.2 in29 mm of precipitation and 10 in25 cm of snow in a typical November.
- Record high
- 66°19° (1975)
- Record low
- −27°−33° (1896)
- Heating degree days
- 1071
- Cooling degree days
- 0
Mammoth in December
Highs average 30°−1° and lows 12°−11°, with 0.91 in23 mm of precipitation and 13 in32 cm of snow in a typical December.
- Record high
- 57°14° (2014)
- Record low
- −35°−37° (1990)
- Heating degree days
- 1361
- Cooling degree days
- 0