Castle Rock weather by month
What a typical year looks like in Castle Rock, Colorado: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at CASTLE ROCK, 2 km from Castle Rock; records cover 1893–2025.
The year at a glance
- Precipitation a year
- 17.6 in447 mm
- Snow a year
- 58 in146 cm
- Last spring freeze
- May 12
- First fall freeze
- Sep 29
- Heating degree days
- 6,104
- Cooling degree days
- 497
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are −3°−19° (heating, 99%) and 95°35° (cooling, 1%).
Month by month
Castle Rock in January
Highs average 46°8° and lows 18°−8°, with 0.55 in14 mm of precipitation and 8 in20 cm of snow in a typical January.
- Record high
- 73°23° (1997)
- Record low
- −37°−38° (1913)
- Heating degree days
- 1029
- Cooling degree days
- 0
Castle Rock in February
Highs average 47°8° and lows 20°−7°, with 0.7 in18 mm of precipitation and 11 in27 cm of snow in a typical February.
- Record high
- 75°24° (1986)
- Record low
- −32°−36° (1899)
- Heating degree days
- 888
- Cooling degree days
- 0
Castle Rock in March
Highs average 54°12° and lows 27°−3°, with 1.5 in39 mm of precipitation and 11 in27 cm of snow in a typical March.
- Record high
- 82°28° (2022)
- Record low
- −20°−29° (1906)
- Heating degree days
- 770
- Cooling degree days
- 0
Castle Rock in April
Highs average 59°15° and lows 33°0°, with 2.1 in53 mm of precipitation and 8 in21 cm of snow in a typical April.
- Record high
- 91°33° (1981)
- Record low
- −8°−22° (1909)
- Heating degree days
- 576
- Cooling degree days
- 1
Castle Rock in May
Highs average 68°20° and lows 42°5°, with 2 in50 mm of precipitation and 1.1 in2.8 cm of snow in a typical May.
- Record high
- 94°34° (2003)
- Record low
- 7°−14° (1907)
- Heating degree days
- 321
- Cooling degree days
- 11
Castle Rock in June
Highs average 80°27° and lows 51°10°, with 2.2 in56 mm of precipitation in a typical June.
- Record high
- 101°38° (2021)
- Record low
- 25°−4° (1924)
- Heating degree days
- 79
- Cooling degree days
- 89
Castle Rock in July
Highs average 86°30° and lows 56°14°, with 2.3 in59 mm of precipitation in a typical July.
- Record high
- 102°39° (2022)
- Record low
- 30°−1° (1895)
- Heating degree days
- 11
- Cooling degree days
- 198
Castle Rock in August
Highs average 84°29° and lows 55°13°, with 2.5 in64 mm of precipitation in a typical August.
- Record high
- 99°37° (1904)
- Record low
- 34°1° (1910)
- Heating degree days
- 21
- Cooling degree days
- 149
Castle Rock in September
Highs average 77°25° and lows 47°8°, with 1.4 in35 mm of precipitation and 0.4 in1 cm of snow in a typical September.
- Record high
- 101°38° (2021)
- Record low
- 11°−12° (1984)
- Heating degree days
- 148
- Cooling degree days
- 47
Castle Rock in OctoberThis month
Highs average 65°18° and lows 35°1°, with 0.85 in22 mm of precipitation and 2.7 in6.9 cm of snow in a typical October.
- Record high
- 88°31° (2020)
- Record low
- −5°−21° (1913)
- Heating degree days
- 477
- Cooling degree days
- 2
Castle Rock in November
Highs average 54°12° and lows 26°−4°, with 0.79 in20 mm of precipitation and 7 in17 cm of snow in a typical November.
- Record high
- 85°29° (1995)
- Record low
- −18°−28° (1976)
- Heating degree days
- 756
- Cooling degree days
- 0
Castle Rock in December
Highs average 46°8° and lows 18°−8°, with 0.69 in18 mm of precipitation and 9 in23 cm of snow in a typical December.
- Record high
- 82°28° (2021)
- Record low
- −29°−34° (1900)
- Heating degree days
- 1028
- Cooling degree days
- 0
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