St. Charles County, MO Climate

St. Charles, MO County has a humid continental climate, with cold winters and hot, humid summers. The average high temperature in January is 33°F, while the average high temperature in July usually reaches 86°F. Precipitation is fairly evenly distributed throughout the year, averaging around 47 inches per year. The area also experiences four distinct seasons and wide variation in temperature between day and night. Snowfall is relatively light compared to other parts of Missouri, averaging around 10 inches per year. Overall, St. Charles has a mild but changing climate that brings warm summer days as well as cold winter nights and occasional snowfall each season.

St. Charles County, Missouri gets 42 inches of rain, on average, per year. The US average is 38 inches of rain per year.

St. Charles County averages 13 inches of snow per year. The US average is 28 inches of snow per year.

On average, there are 202 sunny days per year in St. Charles County. The US average is 205 sunny days.

St. Charles County gets some kind of precipitation, on average, 106 days per year. Precipitation is rain, snow, sleet, or hail that falls to the ground. In order for precipitation to be counted you have to get at least .01 inches on the ground to measure.

Weather Highlights

Summer High: the July high is around 88 degrees
Winter Low: the January low is 21
Rain: averages 42 inches of rain a year
Snow: averages 13 inches of snow a year

Bestplaces Comfort Index

The annual BestPlaces Comfort Index for St. Charles County is 7.2 (10=best), which means it is more comfortable than most places in Missouri.

7.7 Summer - 5.6 Winter

September, May and June are the most pleasant months in St. Charles County, while January and December are the least comfortable months.

Climate	St. Charles, Missouri	United States
	Unlock	38.1 in.
	13.3 in.	Unlock
	Unlock	106.2 days
	202 days	Unlock
	88.2°	85.8°
	Unlock	21.7°
	7.2	Unlock
	Unlock	4.3
	529 ft.	Unlock

Climate

YOU SHOULD KNOW

Many people confuse weather and climate but they are different. Weather is the conditions of the atmosphere over a short period of time, and climate is how the atmosphere is over long periods of time.

Weather is how the atmosphere is behaving and its effects upon life and human activities. Weather can change from minute-to-minute. Most people think of weather in terms of temperature, humidity, precipitation, cloudiness, brightness, visibility, wind, and atmospheric pressure.

Climate is the description of the long-term pattern of weather in a place. Climate can mean the average weather for a particular region and time period taken over 30 years. Climate is the average of weather over time.

July is the hottest month for St. Charles County with an average high temperature of 88.2°, which ranks it as about average compared to other places in Missouri. In St. Charles County, there are 3 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for St. Charles County are September, May and June.

In St. Charles County, there are 33.4 days annually when the high temperature is over 90°, which is about average compared to other places in Missouri.

January has the coldest nighttime temperatures for St. Charles County with an average of 21.1°. This is about average compared to other places in Missouri.

In St. Charles County, there are 101.5 days annually when the nighttime low temperature falls below freezing, which is warmer than most places in Missouri.

In St. Charles County, there are 2.8 days annually when the nighttime low temperature falls below zero°, which is about average compared to other places in Missouri.

The humidity can be uncomfortably heavy or close in St. Charles County during the summer months. July is the most humid month, though humidity is low for most of the year. July, August and June are the three most humid months in St. Charles County.

May is the wettest month in St. Charles County with 4.9 inches of rain, and the driest month is January with 2.4 inches. The wettest season is Summer with 29% of yearly precipitation and 19% occurs in Spring, which is the driest season. The annual rainfall of 42.4 inches in St. Charles County means that it is drier than most places in Missouri.

May is the rainiest month in St. Charles County with 11.5 days of rain, and January is the driest month with only 7.2 rainy days. There are 105.7 rainy days annually in St. Charles County, which is one of the rainiest places in Missouri. The rainiest season is Summer when it rains 30% of the time and the driest is Spring with only a 22% chance of a rainy day.

An annual snowfall of 13.3 inches in St. Charles County means that it is about average compared to other places in Missouri. February is the snowiest month in St. Charles County with 4.2 inches of snow, and 5 months of the year have significant snowfall.

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