Johnstown weather by month
What a typical year looks like in Johnstown, Wyoming: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Pavillion, 15 km from Johnstown; records cover 1919–2026.
The year at a glance
- Precipitation a year
- 8.8 in224 mm
- Snow a year
- 28 in72 cm
- Last spring freeze
- May 14
- First fall freeze
- Sep 27
- Heating degree days
- 7,647
- Cooling degree days
- 373
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 94°34° (cooling, 1%).
Month by month
Johnstown in January
Highs average 34°1° and lows 10°−12°, with 0.27 in6.9 mm of precipitation and 4 in10 cm of snow in a typical January.
- Record high
- 63°17° (1953)
- Record low
- −38°−39° (1930)
- Heating degree days
- 1342
- Cooling degree days
- 0
Johnstown in February
Highs average 38°3° and lows 14°−10°, with 0.28 in7.1 mm of precipitation and 5 in12 cm of snow in a typical February.
- Record high
- 70°21° (1951)
- Record low
- −39° (1936)
- Heating degree days
- 1102
- Cooling degree days
- 0
Johnstown in March
Highs average 50°10° and lows 23°−5°, with 0.43 in11 mm of precipitation and 4 in9 cm of snow in a typical March.
- Record high
- 80°27° (2026)
- Record low
- −20°−29° (1922)
- Heating degree days
- 874
- Cooling degree days
- 0
Johnstown in April
Highs average 58°14° and lows 31°−1°, with 1.1 in27 mm of precipitation and 5 in12 cm of snow in a typical April.
- Record high
- 84°29° (1939)
- Record low
- −13°−25° (1936)
- Heating degree days
- 620
- Cooling degree days
- 0
Johnstown in May
Highs average 67°19° and lows 40°4°, with 2.1 in53 mm of precipitation and 0.4 in1 cm of snow in a typical May.
- Record high
- 96°36° (2003)
- Record low
- 17°−8° (1984)
- Heating degree days
- 361
- Cooling degree days
- 4
Johnstown in June
Highs average 77°25° and lows 48°9°, with 1.1 in29 mm of precipitation and 0.2 in0.5 cm of snow in a typical June.
- Record high
- 102°39° (1919)
- Record low
- 25°−4° (1982)
- Heating degree days
- 124
- Cooling degree days
- 48
Johnstown in July
Highs average 86°30° and lows 55°13°, with 0.73 in19 mm of precipitation in a typical July.
- Record high
- 101°38° (1925)
- Record low
- 35°2° (1986)
- Heating degree days
- 15
- Cooling degree days
- 177
Johnstown in August
Highs average 83°28° and lows 53°12°, with 0.56 in14 mm of precipitation in a typical August.
- Record high
- 100°38° (2003)
- Record low
- 34°1° (1932)
- Heating degree days
- 31
- Cooling degree days
- 126
Johnstown in September
Highs average 74°23° and lows 44°7°, with 0.87 in22 mm of precipitation and 0.3 in0.8 cm of snow in a typical September.
- Record high
- 97°36° (1950)
- Record low
- 15°−9° (1985)
- Heating degree days
- 203
- Cooling degree days
- 18
Johnstown in OctoberThis month
Highs average 59°15° and lows 32°0°, with 0.74 in19 mm of precipitation and 1.9 in4.8 cm of snow in a typical October.
- Record high
- 84°29° (1920)
- Record low
- −10°−23° (2020)
- Heating degree days
- 605
- Cooling degree days
- 0
Johnstown in November
Highs average 44°7° and lows 19°−7°, with 0.35 in8.9 mm of precipitation and 3 in9 cm of snow in a typical November.
- Record high
- 72°22° (2020)
- Record low
- −22°−30° (1978)
- Heating degree days
- 1006
- Cooling degree days
- 0
Johnstown in December
Highs average 33°0° and lows 9°−13°, with 0.28 in7.1 mm of precipitation and 5 in12 cm of snow in a typical December.
- Record high
- 65°18° (1980)
- Record low
- −42°−41° (1924)
- Heating degree days
- 1364
- Cooling degree days
- 0