The remote server returned an error: (400) Bad Request.The remote server returned an error: (400) Bad Request. 2025 Compare Climate & Weather: Simi Valley, CA vs Castle Rock, CO

2025 Compare Climate & Weather:
Simi Valley, CA vs Castle Rock, CO

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Highlights

On average, there are 243 sunny days per year in Castle Rock. Simi Valley averages 277 sunny days per year. The US average is 205 sunny days.

Castle Rock, Colorado gets 18.6 inches of rain, on average, per year. Simi Valley, California gets 17.2 inches of rain, on average, per year. The US average is 38.1 inches of rain per year.

Castle Rock averages 78.3 inches of snow per year. Simi Valley averages 0 inches of snow per year. The US average is 27.8 inches of snow per year.

Weather Highlights

Castle Rock, Colorado
Summer High: the July high is around 85.5 degrees
Winter Low: the January low is 18.6
Rain: averages 18.6 inches of rain a year
Snow: averages 78.3 inches of snow a year

Simi Valley, California
Summer High: the July high is around 92.2 degrees
Winter Low: the January low is 41.5
Rain: averages 17.2 inches of rain a year
Snow: averages 0 inches of snow a year

BestPlaces Comfort Index
Castle Rock

The annual BestPlaces Comfort Index for Castle Rock is 7.2 (10=best), which means it is more comfortable than most places in Colorado.

7.2 / 10
August, September and July are the most pleasant months in Castle Rock, while December and January are the least comfortable months.

Simi Valley

The annual BestPlaces Comfort Index for Simi Valley is 8.6 (10=best), which means it is more comfortable than most places in California.

8.6 / 10
May, October and June are the most pleasant months in Simi Valley, while August and July are the least comfortable months.

Average Monthly High / Low (°F)
MonthSimi Valley, CACastle Rock, CO
January68° / 42°45° / 19°
February68° / 42°46° / 20°
March72° / 44°53° / 26°
April76° / 46°60° / 32°
May80° / 51°69° / 41°
June86° / 55°79° / 50°
July92° / 59°86° / 56°
August94° / 58°83° / 55°
September90° / 57°76° / 47°
October82° / 51°65° / 36°
November74° / 45°52° / 26°
December68° / 41°44° / 18°
Hot, Freezing, Rainy, Snowy Days: Simi Valley / Castle Rock
MonthHot DaysFreezing DaysRainy DaysSnowy Days
January0 / 03 / 296 / 30 / 4
February0 / 02 / 257 / 40 / 4
March1 / 01 / 235 / 60 / 5
April3 / 00 / 153 / 60 / 4
May6 / 00 / 31 / 90 / 1
June10 / 20 / 00 / 80 / 0
July19 / 80 / 00 / 80 / 0
August21 / 40 / 00 / 100 / 0
September16 / 10 / 11 / 60 / 0
October7 / 00 / 103 / 40 / 1
November1 / 01 / 223 / 40 / 4
December0 / 03 / 285 / 40 / 4
August is the hottest month for Simi Valley with an average high temperature of 93.5°, which ranks it as warmer than most places in California. In Simi Valley, there are 5 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Simi Valley are April, May and November.

July is the hottest month for Castle Rock with an average high temperature of 85.5°, which ranks it as about average compared to other places in Colorado. In Castle Rock, there are 3 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Castle Rock are June, September and August.
December has the coldest nighttime temperatures for Simi Valley with an average of 40.5°. This is warmer than most places in California.

December has the coldest nighttime temperatures for Castle Rock with an average of 18.1°. This is one of the warmest places in Colorado.

In Simi Valley, there are 82.8 days annually when the high temperature is over 90°, which is hotter than most places in California.

In Castle Rock, there are 14.9 days annually when the high temperature is over 90°, which is cooler than most places in Colorado.

In Simi Valley, there are 9.2 days annually when the nighttime low temperature falls below freezing, which is warmer than most places in California.

In Castle Rock, there are 156.4 days annually when the nighttime low temperature falls below freezing, which is warmer than most places in Colorado.

In Simi Valley, there are 0.0 days annually when the nighttime low temperature falls below zero°, which is about average compared to other places in California.

In Castle Rock, there are 5.6 days annually when the nighttime low temperature falls below zero°, which is warmer than most places in Colorado.

February is the wettest month in Simi Valley with 4.3 inches of rain, and the driest month is July with 0.0 inches. The wettest season is Spring with 62% of yearly precipitation and 1% occurs in Autumn, which is the driest season. The annual rainfall of 17.2 inches in Simi Valley means that it is about average compared to other places in California.


August is the wettest month in Castle Rock with 2.6 inches of rain, and the driest month is January with 0.6 inches. The wettest season is Autumn with 40% of yearly precipitation and 10% occurs in Spring, which is the driest season. The annual rainfall of 18.6 inches in Castle Rock means that it is wetter than most places in Colorado.

February is the rainiest month in Simi Valley with 6.6 days of rain, and July is the driest month with only 0.2 rainy days. There are 35.0 rainy days annually in Simi Valley, which is less rainy than most places in California. The rainiest season is Spring when it rains 51% of the time and the driest is Autumn with only a 3% chance of a rainy day.

August is the rainiest month in Castle Rock with 9.9 days of rain, and January is the driest month with only 3.3 rainy days. There are 70.0 rainy days annually in Castle Rock, which is less rainy than most places in Colorado. The rainiest season is Autumn when it rains 37% of the time and the driest is Spring with only a 15% chance of a rainy day.

There is rarely any recorded snowfall in Simi Valley, ranking it as one of the least snowy places in California.

An annual snowfall of 78.3 inches in Castle Rock means that it is snowier than most places in Colorado.
Any measurable snowfall is a rare occurance in Simi Valley.

March is the snowiest month in Castle Rock with 16.8 inches of snow, and 9 months of the year have significant snowfall.

DID YOU KNOW?

Many people confuse Weather and Climate, but they are different. Weather refers to the conditions of the atmosphere over a short period of time, while Climate refers to the conditions of the atmosphere over a long period of time.

Weather, more specifically, refers to how the atmosphere behaves and its effects on life and human activities. Most people think of Weather in terms of what can be observed: temperature, humidity, precipitation, and cloudy/sunny conditions. Weather conditions constantly change on a minute-to-minute basis.

Climate is a record of the average weather conditions for a given place over a long period of time, often referred to as Climate Normals. A 30-year period of record is a common requirement to be considered a Climate Normal.

Reviews for Simi Valley    2 Reviews
Jill · Sherman Oaks, CA
re:
Over 16 years ago

Hi. I'd like to know if you still feel the same way about living in Broomfield. I went there this past July to check it out (along with Lafayette, Boulder (can't  More

   |    Reply
NC For Me · Apex, NC
re:
Over 16 years ago

Apex is perfect for what you are looking for. It's close enough to Raleigh, Durham, Chapel Hill to find a job and Cary the next town over, is a little more expensive but  More

   |    Reply

Start Your Review of Simi Valley

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Reviews for Castle Rock    2 Reviews
Jill · Sherman Oaks, CA
re:
Over 16 years ago

Hi. I'd like to know if you still feel the same way about living in Broomfield. I went there this past July to check it out (along with Lafayette, Boulder (can't  More

   |    Reply
NC For Me · Apex, NC
re:
Over 16 years ago

Apex is perfect for what you are looking for. It's close enough to Raleigh, Durham, Chapel Hill to find a job and Cary the next town over, is a little more expensive but  More

   |    Reply

Start Your Review of Castle Rock

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Zips In Simi Valley, California
93065, 93063
Zips In CASTLE ROCK, COLORADO
80104, 80109
Learn More About SIMI VALLEY, CALIFORNIA
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