Castle Rock climate — normals and trends
Castle Rock (United States) has a warm-summer humid continental climate (Dfb) under the Köppen-Geiger classification. Its mean annual temperature is 6.7 °C and it receives 531 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is July (19.5 °C on average) and the coldest is January (-5.2 °C). Rainfall peaks in May.
Castle Rock averages 185 frost days, 13 hot days (≥ 30 °C) and 97 rainy days per year.
Castle Rock has warmed by +2.3 °C between 1940 and 2025, or +0.27 °C per decade. This trend is statistically significant.
The number of frost days there went from about 195 to 175 per year over the period.
The hottest day of the period reached 35.9 °C (on 23 June 1954) and the coldest -42.6 °C (on 1 February 1951).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
Castle RockColorado
- coords
- 39.37°, -104.86°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
6.7°C
Average daily high
14.5°C
Average daily low
-0.4°C
Annual rainfall
531mm
Sunshine / day
10.8h
Mean relative humidity
57%
Average peak wind
15.0km/h
Seasonal range
24.7°C
Frost days (< 0 °C)
185 d/yr
Hot days (≥ 30 °C)
13 d/yr
Rainy days (≥ 1 mm)
97 d/yr
Annual snowfall
138.8 cm
Average feels-like high
11.6 °C
Average feels-like low
-4.0 °C
Average peak gust
34.9 km/h
Tropical nights (≥ 20 °C)
0 d/yr
Solar radiation
18.6 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.3 °C
since 1940
+0.3 °C per decade · r² = 0.42 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
35.9 °C
23 June 1954
Coldest day
-42.6 °C
1 February 1951
Wettest day
86 mm
23 July 1991
Windiest day
48.0 km/h
23 March 1957
Strongest gust
106.9 km/h
6 June 2020
Hottest feels-like
34.6 °C
23 June 1954
Coldest feels-like
-48.1 °C
1 February 1951
Snowiest day
44.9 cm
3 April 1986
Sunniest day
14.1 h
27 June 1941
Normals computed over complete calendar years 1940–2025.
A specific year
Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?
Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 0.6 °C | -2.8 °C | 28 mm | +10 mm |
| Feb | 6.5 °C | +1.6 °C | 16 mm | -5 mm |
| Mar | 12.5 °C | +4.6 °C | 30 mm | -16 mm |
| Apr | 14.8 °C | +2.5 °C | 26 mm | -42 mm |
| May | 18.6 °C | +1.0 °C | 84 mm | -1 mm |
| Jun | 25.1 °C | +1.1 °C | 71 mm | +15 mm |
| Jul | 28.7 °C | +1.6 °C | 60 mm | -3 mm |
| Aug | 27.7 °C | +1.7 °C | 75 mm | +18 mm |
| Sep | 22.5 °C | +0.2 °C | 43 mm | +4 mm |
| Oct | 18.6 °C | +2.6 °C | 16 mm | -20 mm |
| Nov | 13.6 °C | +5.3 °C | 12 mm | -14 mm |
| Dec | 10.9 °C | +6.8 °C | 13 mm | -5 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of Castle Rock?
Castle Rock has a warm-summer humid continental climate (Köppen Dfb). Over 1940-2025, the average annual temperature is 6.7 °C and it receives 531 mm of precipitation per year.
What is the hottest day ever recorded in Castle Rock?
The hottest day measured in Castle Rock between 1940 and 2025 was 23 June 1954, reaching 35.9 °C.
What is the coldest day in Castle Rock?
The coldest day measured in Castle Rock between 1940 and 2025 was 1 February 1951, at -42.6 °C.
Does it snow in Castle Rock?
Yes. Castle Rock gets on average 138.8 cm of snow per year and has around 185 frost days.
Has the climate of Castle Rock warmed?
Yes: Castle Rock warmed by +2.3 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Castle Rock?
The wettest day measured in Castle Rock between 1940 and 2025 was 23 July 1991, with 86 mm of rain in 24 hours.
What was the windiest day in Castle Rock?
The windiest day measured in Castle Rock between 1940 and 2025 was 23 March 1957, with winds reaching 48.0 km/h.
What is the warmest month in Castle Rock?
The warmest month in Castle Rock is July (19.5 °C on average); the coldest is January (-5.2 °C).
How much does it rain in Castle Rock?
Castle Rock receives on average 531 mm of precipitation per year, spread over about 97 rainy days.
Is it sunny in Castle Rock?
Castle Rock gets on average 10.8 hours of sunshine per day, roughly 3,942 hours per year over 1940-2025.
What is the biggest single-day snowfall in Castle Rock?
The heaviest 24-hour snowfall measured in Castle Rock between 1940 and 2025 was 3 April 1986, with 44.9 cm.
Are there tropical nights in Castle Rock?
Almost never: tropical nights (temperature staying above 20 °C) are virtually non-existent in Castle Rock.
What was the most extreme apparent temperature in Castle Rock?
In Castle Rock, between 1940 and 2025, the highest apparent temperature reached 34.6 °C on 23 June 1954, and the lowest was -48.1 °C on 1 February 1951.
Compare Castle Rock with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Castle Rock