2025 Compare Climate & Weather:
Black Diamond, WA vs Charleston, SC

Highlights

On average, there are 209 sunny days per year in Charleston. Black Diamond averages 156 sunny days per year. The US average is 205 sunny days.

Charleston, South Carolina gets 48.3 inches of rain, on average, per year. Black Diamond, Washington gets 50 inches of rain, on average, per year. The US average is 38.1 inches of rain per year.

Charleston averages 0.4 inches of snow per year. Black Diamond averages 4.7 inches of snow per year. The US average is 27.8 inches of snow per year.

Weather Highlights

Charleston, South Carolina
Summer High: the July high is around 89.9 degrees
Winter Low: the January low is 39.3
Rain: averages 48.3 inches of rain a year
Snow: averages 0.4 inches of snow a year

Black Diamond, Washington
Summer High: the July high is around 75.7 degrees
Winter Low: the January low is 34.7
Rain: averages 50 inches of rain a year
Snow: averages 4.7 inches of snow a year

BestPlaces Comfort Index

The annual BestPlaces Comfort Index for Charleston is 7.2 (10=best), which means it is less comfortable than most places in South Carolina.

The annual BestPlaces Comfort Index for Black Diamond is 7.0 (10=best), which means it is less comfortable than most places in Washington.

Today's Weather - Black Diamond, WA

70°F

Today's Weather - Charleston, SC

75°F

Average Monthly High / Low (°F)

Hot, Freezing, Rainy, Snowy Days: Black Diamond / Charleston

August is the hottest month for Black Diamond with an average high temperature of 76.4°, which ranks it as cooler than most places in Washington. In Black Diamond, there are 3 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Black Diamond are August, July and September.

July is the hottest month for Charleston with an average high temperature of 89.9°, which ranks it as cooler than most places in South Carolina. In Charleston, there are 4 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Charleston are October, May and April.

December has the coldest nighttime temperatures for Black Diamond with an average of 33.2°. This is about average compared to other places in Washington.

January has the coldest nighttime temperatures for Charleston with an average of 39.3°. This is one of the warmest places in South Carolina.

In Black Diamond, there are 3.3 days annually when the high temperature is over 90°, which is about average compared to other places in Washington.

In Charleston, there are 41.1 days annually when the high temperature is over 90°, which is cooler than most places in South Carolina.

In Black Diamond, there are 49.9 days annually when the nighttime low temperature falls below freezing, which is about average compared to other places in Washington.

In Charleston, there are 17.5 days annually when the nighttime low temperature falls below freezing, which is one of the warmest places in South Carolina.

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

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

November is the wettest month in Black Diamond with 7.9 inches of rain, and the driest month is July with 1.3 inches. The wettest season is Spring with 34% of yearly precipitation and 11% occurs in Autumn, which is the driest season. The annual rainfall of 50.0 inches in Black Diamond means that it is wetter than most places in Washington.


August is the wettest month in Charleston with 6.7 inches of rain, and the driest month is May with 2.5 inches. The wettest season is Autumn with 36% of yearly precipitation and 19% occurs in Summer, which is the driest season. The annual rainfall of 48.3 inches in Charleston means that it is wetter than most places in South Carolina.

November is the rainiest month in Black Diamond with 20.3 days of rain, and August is the driest month with only 5.8 rainy days. There are 173.6 rainy days annually in Black Diamond, which is rainier than most places in Washington. The rainiest season is Spring when it rains 31% of the time and the driest is Autumn with only a 14% chance of a rainy day.

August is the rainiest month in Charleston with 11.7 days of rain, and May is the driest month with only 6.8 rainy days. There are 105.9 rainy days annually in Charleston, which is rainier than most places in South Carolina. The rainiest season is Autumn when it rains 32% of the time and the driest is Summer with only a 21% chance of a rainy day.

An annual snowfall of 4.7 inches in Black Diamond means that it is about average compared to other places in Washington.

An annual snowfall of 0.4 inches in Charleston means that it is less snowy than most places in South Carolina.

November is the snowiest month in Black Diamond with 1.4 inches of snow, and 4 months of the year have significant snowfall.

December is the snowiest month in Charleston with 0.2 inches of snow, and no months of the year have significant snowfall.