Castle Rock, CO Climate: Temperature & Rain by Month
Annual temperature and rainfall from NOAA NCEI's 1991–2020 normals →; comfort score computed by PlainClimate
30-year climate normals (1991-2020) from Castle Rock's primary NOAA station, CASTLE ROCK.
The climate verdict for Castle Rock
Dryness leads the climate profile for Castle Rock, Colorado, with 17.6 inches of precipitation a year. NOAA records an annual average of 50°F. At 44/100 (moderate) the climate comfort score falls in the bottom third of the station-mapped U.S. score corpus, exceeding only 10% of scores.
- 50°F
- annual average temperature (NOAA normal)
- 44/100
- comfort score, above 10% of station-mapped location scores
- 17.6"
- annual precipitation · 58" snow
- 146 days
- frost-free growing season
Castle Rock: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USC00051401 · Castle Rock, CO 50°F mean · 17.6" precip
TEMP-COOL · RANK-COOL · PHOTO-FINISH · PRCP-DRY · SWING-MID · COMF-LOW · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-COOL 50°F
- RANK-COOL #2,607
- PHOTO-FINISH ≈ Donegal
- PRCP-DRY 17.6"
- SWING-MID 39°F
- COMF-LOW 44/100
- LOAD-HEAT 6,103 HDD
- STN-1 USC00051401
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Donegal, PA (+ 0 °F mean)
Instrument codes from this station's NOAA 1991–2020 normals, mean temperature, corpus warmth rank, photo-finish peer station, precipitation band, seasonal swing, comfort composite, degree-day load, and field book, not a livability rating.
Mean-temperature neighbourhood
Nationwide NOAA normal poles and nearest peers, not a reprint of every CO station list.
- Castle Rock (this station) 50°F
- Hot Oakley, ID 50°F
- Near Donegal, PA 50°F
- Near Gallup, NM 50°F
- Cold La Grande, OR 49°F
Climate Living Index · Castle Rock
Castle Rock: 31/100 · grade F
Castle Rock publishes 5 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 1 missing weight rescale to 100.
PlainClimate-derived for Castle Rock, not an official NOAA rating. Rankings still use Comfort Score 44/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Annual temperature balance | 49.6°F · 17.9° from 67.5°F | 39/100 · F |
| Precipitation balance | 17.6 in · 17.4 from 35 in | 38/100 · F |
| Normal heat + freeze calendar | 174 calendar days | 29/100 · F |
| Frost-free season | 146 days/year | 22/100 · F |
| Snowfall burden | 57.5 inches/year | 17/100 · F |
Castle Rock · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Castle Rock's normals sit in a dry climate class: BSk
Precipitation is low relative to temperature but above true desert thresholds: cold semi-arid steppe (BSk). Class BSk is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: dry (arid or semi-arid), specifically cold semi-arid steppe.
- Köppen code
- BSk
- Group
- Dry (arid or semi-arid)
- Warmest month
- 71.1°F
- Coldest month
- 31.8°F
Source: official public datasets monthly normals (1991–2020) at the city’s primary station. This is a station classification, not a mapped regional consensus.
National standing · heating-led station
Where Castle Rock sits across the climate record
Three NOAA fields for Castle Rock's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- 38th percentile warmth
- Mid-pack annual mean versus 6,861 station normals.
- Annual precipitation
- Drier than 77%
- Castle Rock's annual total ranks in the drier third of 6,352 measured normals.
- Seasonal temperature swing
- 33rd percentile swing
- Typical seasonal amplitude versus 6,861 complete station-years.
How Castle Rock compares across U.S. station-mapped locations
Castle Rock's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
44 10th percentile score exceeds 10% of 6,189 station-mapped location scores
- 0–10: 0 station-mapped locations (0%). Below this entry.
- 10–20: 0 station-mapped locations (0%). Below this entry.
- 20–30: 96 station-mapped locations (2%). Below this entry.
- 30–40: 280 station-mapped locations (5%). Below this entry.
- 40–50: 1,113 station-mapped locations (18%). This entry sits in this band.
- 50–60: 1,329 station-mapped locations (21%). Above this entry.
- 60–70: 1,236 station-mapped locations (20%). Above this entry.
- 70–80: 650 station-mapped locations (11%). Above this entry.
- 80–90: 921 station-mapped locations (15%). Above this entry.
- 90–100: 564 station-mapped locations (9%). Above this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Castle Rock's measured station temperature trend
MethodologyAcross 32 complete annual observations from 1963 to 2024, CASTLE ROCK warmed at a fitted rate of 0.16°C per decade. The line shows the fitted change relative to its first year, not raw year-to-year temperatures or a forecast.
- Castle Rock primary station fitted change +0.16 °C/decade
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Snow | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|---|
| January | 46°F (8°C) | 18°F (-8°C) | 32°F (0°C) | 0.6" | 8.0" | 29.5 | 0.0 |
| February | 47°F (8°C) | 20°F (-7°C) | 33°F (1°C) | 0.7" | 10.7" | 26.1 | 0.0 |
| March | 54°F (12°C) | 27°F (-3°C) | 40°F (5°C) | 1.5" | 10.7" | 24.1 | 0.0 |
| April | 59°F (15°C) | 33°F (0°C) | 46°F (8°C) | 2.1" | 8.3" | 16.5 | 0.0 |
| May | 68°F (20°C) | 42°F (5°C) | 55°F (13°C) | 2.0" | 1.1" | 3.9 | 0.4 |
| June | 80°F (27°C) | 51°F (10°C) | 65°F (19°C) | 2.2" | 0.0" | 0.1 | 4.3 |
| July | 86°F (30°C) | 56°F (14°C) | 71°F (22°C) | 2.3" | 0.0" | 0.0 | 10.8 |
| August | 84°F (29°C) | 55°F (13°C) | 69°F (21°C) | 2.5" | 0.0" | 0.0 | 6.0 |
| September | 77°F (25°C) | 47°F (8°C) | 62°F (17°C) | 1.4" | 0.4" | 1.2 | 1.6 |
| October | 65°F (18°C) | 35°F (1°C) | 50°F (10°C) | 0.8" | 2.7" | 12.4 | 0.0 |
| November | 54°F (12°C) | 26°F (-4°C) | 40°F (4°C) | 0.8" | 6.7" | 23.8 | 0.0 |
| December | 46°F (8°C) | 18°F (-8°C) | 32°F (0°C) | 0.7" | 8.9" | 29.1 | 0.0 |
The year, day by day
Summer here tops out rather than builds: the warmest normal high is 86°F around July 14, short of 90°F on every date, while 174 dates carry a normal low at or below freezing, the coldest 17°F near December 22.
The freezing stretch
The normal low stays at or below 32°F into April 14, then returns to freezing around October 24, covering 174 dates in all.
Derived from the normal daily minimum. This is a different measure from the 50%-probability frost dates shown elsewhere on this page, which come from NOAA’s frost product.
Where the wet dates fall
The likeliest wet date is August 6, when 32% of years recorded at least a hundredth of an inch. The driest is January 9 at 13%. Summed across the calendar, that is about 74 wet dates a year.
The widest day
October 5 carries the biggest normal gap between afternoon and dawn, 31°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Castle Rock.
Monthly Precipitation
Average monthly rainfall and snowfall
Snow: 8.0"
4.1 days with precipitation
Snow: 10.7"
4.9 days with precipitation
Snow: 10.7"
5.0 days with precipitation
Snow: 8.3"
6.4 days with precipitation
Snow: 1.1"
8.3 days with precipitation
7.7 days with precipitation
8.3 days with precipitation
10.1 days with precipitation
Snow: 0.4"
5.8 days with precipitation
Snow: 2.7"
4.4 days with precipitation
Snow: 6.7"
4.1 days with precipitation
Snow: 8.9"
4.6 days with precipitation
Castle Rock runs a summer-peaked wet season
40% of Castle Rock's yearly precipitation falls in June, July and August alone, against the 25% an evenly spread year would give those three months. The wettest month is August at 2.5", on a 39.3°F seasonal spread. Warm-season convection and, across the Southwest, the North American monsoon produce this shape: rain arrives in short heavy bursts during the hottest part of the year rather than as long cool-season soaking.
- Wettest three months: August, July, June, taking 40% of the annual total between them.
- Driest month: January at 0.6".
- Winter share: 11% falls in December, January and February.
Shares are computed from this station's own 1991-2020 monthly precipitation normals. A summer-peaked label means the June-August share reaches 35%; it describes timing across an average year, not any single season, and says nothing about how heavy an individual storm can be.
How Castle Rock's precipitation splits across the calendar
About 74 days a year record measurable precipitation here, carrying 17.6" between them, or roughly 0.24 inches on a typical wet day. That sits in the middle band: neither the many-light-days pattern of the Pacific Northwest and the Great Lakes, nor the few-heavy-events pattern of the Gulf and the desert Southwest.
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year and say nothing about the heaviest single storm on record.
Winter brings real snow to Castle Rock
Castle Rock averages 57.5 inches of snowfall a year, with February the snowiest month on the normals, spread across roughly 23 days that record measurable snow. That is depth accumulating on the ground, which is why it can exceed the annual precipitation figure: precipitation counts the liquid the snow melts down to, and fresh snow is mostly air.
- Annual snowfall: 57.5 inches of depth.
- Days recording measurable snow: about 23 a year.
- At a rough ten-to-one melt ratio, snow accounts for on the order of 33% of the year's precipitation.
NOAA 1991-2020 normals. The ten-to-one ratio is a convention, not a measurement: real ratios vary with temperature, so treat the share as an order of magnitude rather than an exact split.
Frost Dates & Growing Season
First Fall Freeze
October 2
50% probability date
Last Spring Freeze
May 9
50% probability date
Growing Season
146 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
6,103
Higher = more heating needed
Cooling Degree Days
499
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
Nationwide similar cities
Other rankable U.S. places outside CO closest to Castle Rock on two NOAA annual-normal axes (mean temperature and annual precipitation). Chip rows use distinct link sets.
Closest by average temperature
Nearest out-of-state peers by annual mean temperature (50°F here).
- Altoona, PA 50°F · 0.0°F off
- Donegal, PA 50°F · 0.0°F off
- Hershey, NE 50°F · 0.0°F off
- Kewanee, IL 50°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (17.6" here), excluding temperature-peer places.
- Capulin, NM 17.6" · 0.0" off
- Gillette, WY 17.6" · 0.0" off
- Morton, TX 17.6" · 0.0" off
- Pomeroy, WA 17.6" · 0.0" off
Snow and freeze rhythm
When cold and snow define Castle Rock
heating led · dry · mid swing
Castle Rock's energy balance leans toward cold weather: 6,103 annual heating degree days against 499 for cooling. Its 39.3°F seasonal range still makes the monthly rows more useful than the annual average alone.
Only about 146 days are frost-free in a normal year. That short interval is consistent with the cold-season signal, but the measure does not predict the exact first or last freeze in any one year.
-
1. Castle Rock coldest normal
January
The monthly mean of 32°F (0°C) sits near freezing, so cold nights and above-freezing afternoons share the same month.
-
2. Castle Rock typical freeze period
January through December
The station reports average freezing days from January through December.
-
3. Castle Rock snow peak
February
Castle Rock averages 57.5 inches of snow a year, with February the snowiest month on the normals.
Questions about Castle Rock's climate
How much snow does Castle Rock get? ▼
How cold does Castle Rock get in winter? ▼
How much energy does heating and cooling require in Castle Rock? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Castle Rock's primary station: CASTLE ROCK (USC00051401). For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The 2024 Census Gazetteer identifies the exact name-and-state match as an incorporated place (GEOID 0812415). Match rule for Castle Rock: exact normalized name + state only, no fuzzy expansion, so nearby differently spelled facilities stay unmatched.
On this page every temperature, precipitation, and derived score for Castle Rock comes from its primary NOAA station record. No figure on this page is typed in by an editor - each value is rendered from NOAA 1991-2020 U.S. Climate Normals. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 1991–2020 normals.