Castle Rock, CO climate
Castle Rock has chilly, snowy winters and warm summers, with very little rain. A typical July afternoon reaches 85°, a January night drops to 18°, and about 58 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Castle Rock feels like
Winter
Spring
Summer
Fall
Castle Rock weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 45° | 18° | 0.6" | 8.0" | 4 | 12 | 23° – 37° |
| February | 46° | 19° | 0.7" | 10.7" | 5 | 9 | 27° – 39° |
| March | 53° | 26° | 1.5" | 10.7" | 5 | 5 | 34° – 46° |
| April | 59° | 32° | 2.2" | 8.3" | 6 | 4 | 40° – 51° |
| May | 68° | 41° | 2.2" | 1.1" | 8 | 1 | 47° – 58° |
| June | 80° | 50° | 1.9" | 0 | 8 | 0 | 61° – 70° |
| July | 85° | 56° | 2.3" | 0 | 8 | 0 | 67° – 74° |
| August | 83° | 55° | 2.2" | 0 | 10 | 0 | 64° – 72° |
| September | 76° | 47° | 1.4" | 0.4" | 6 | 0 | 56° – 66° |
| October | 64° | 35° | 1.1" | 2.7" | 4 | 2 | 41° – 55° |
| November | 53° | 25° | 0.8" | 6.7" | 4 | 5 | 30° – 46° |
| December | 44° | 18° | 0.7" | 8.9" | 5 | 11 | 24° – 36° |
| Year | 63° | 35° | 17.7" | 57.5" | 74 | 48 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in Castle Rock
Castle Rock gets 18 inches of rain and melted snow a year. July is the wettest month and January the driest. Rain or snow falls on about 74 days a year. Snow covers the ground about 48 days of the year.
About 143 frost-free days a year
In half of years the last 32° night comes by May 9 and the first one by October 2. That leaves about 143 frost-free days for gardens, shorter than 87% of U.S. towns.
Heating and cooling a home in Castle Rock
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Castle Rock, 92% of that work is heating and 8% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
Castle Rock and its neighbors
Castle Rock borders 3 towns with climate data. January nights across them vary by 2.2°. The Pinery has the coldest January nights (17°) and Castle Pines Village the hottest July afternoons (86°). Castle Rock’s January low is 18° and its July high 85°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Castle Rock compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in Castle Rock averaged 1.2° warmer than the 1900s. The biggest change is in March (+3.1°). The shift is larger than in 51% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Castle Rock’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. November swings the most: between 1991 and 2020 its average temperature ranged from 30° to 46°. July is the most reliable, staying within 7°.
Common questions about Castle Rock’s climate
What is the coldest month in Castle Rock?
January, with a typical high of 45° and a low of 18°.
What is the hottest month in Castle Rock?
July, with a typical high of 85° and a low of 56°. About 23 days a year reach 90°.
How much snow does Castle Rock get?
About 58 inches in a normal winter, most of it in February.
When is the first frost in Castle Rock?
In half of years the first 32° night comes by October 2, and the last spring frost by May 9.
What is the rainiest month in Castle Rock?
July, with 2.3 inches of rain and melted snow. The year totals 18 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Castle Rock itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Castle Rock, CO (4 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.