2025 Compare Climate & Weather:
Keystone, SD vs Rapid City, SD

Highlights

On average, there are 226 sunny days per year in Rapid City. Keystone averages 222 sunny days per year. The US average is 205 sunny days.

Rapid City, South Dakota gets 18.2 inches of rain, on average, per year. Keystone, South Dakota gets 20.1 inches of rain, on average, per year. The US average is 38.1 inches of rain per year.

Rapid City averages 38 inches of snow per year. Keystone averages 54.1 inches of snow per year. The US average is 27.8 inches of snow per year.

Weather Highlights

Rapid City, South Dakota
Summer High: the July high is around 85.3 degrees
Winter Low: the January low is 14.2
Rain: averages 18.2 inches of rain a year
Snow: averages 38 inches of snow a year

Keystone, South Dakota
Summer High: the July high is around 81.2 degrees
Winter Low: the January low is 12.1
Rain: averages 20.1 inches of rain a year
Snow: averages 54.1 inches of snow a year

BestPlaces Comfort Index

The annual BestPlaces Comfort Index for Rapid City is 7.0 (10=best), which means it is one of the most pleasant places in South Dakota.

The annual BestPlaces Comfort Index for Keystone is 6.7 (10=best), which means it is less comfortable than most places in South Dakota.

Today's Weather - Keystone, SD

63°F

Today's Weather - Rapid City, SD

67°F

Average Monthly High / Low (°F)

Hot, Freezing, Rainy, Snowy Days: Keystone / Rapid City

July is the hottest month for Keystone with an average high temperature of 81.2°, which ranks it as one of the coolest places in South Dakota. In Keystone, there are 4 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Keystone are August, July and June.

July is the hottest month for Rapid City with an average high temperature of 85.3°, which ranks it as about average compared to other places in South Dakota. In Rapid City, there are 3 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Rapid City are June, September and August.

December has the coldest nighttime temperatures for Keystone with an average of 11.6°. This is warmer than most places in South Dakota.

January has the coldest nighttime temperatures for Rapid City with an average of 14.2°. This is one of the warmest places in South Dakota.

In Keystone, there are 9.3 days annually when the high temperature is over 90°, which is cooler than most places in South Dakota.

In Rapid City, there are 22.5 days annually when the high temperature is over 90°, which is about average compared to other places in South Dakota.

In Keystone, there are 194.3 days annually when the nighttime low temperature falls below freezing, which is one of the coldest places in South Dakota.

In Rapid City, there are 159.6 days annually when the nighttime low temperature falls below freezing, which is warmer than most places in South Dakota.

In Keystone, there are 17.9 days annually when the nighttime low temperature falls below zero°, which is warmer than most places in South Dakota.

In Rapid City, there are 14.9 days annually when the nighttime low temperature falls below zero°, which is one of the warmest places in South Dakota.

May is the wettest month in Keystone with 3.7 inches of rain, and the driest month is January with 0.3 inches. The wettest season is Autumn with 41% of yearly precipitation and 6% occurs in Spring, which is the driest season. The annual rainfall of 20.1 inches in Keystone means that it is drier than most places in South Dakota.


May is the wettest month in Rapid City with 3.8 inches of rain, and the driest month is January with 0.3 inches. The wettest season is Autumn with 38% of yearly precipitation and 6% occurs in Spring, which is the driest season. The annual rainfall of 18.2 inches in Rapid City means that it is drier than most places in South Dakota.

May is the rainiest month in Keystone with 11.6 days of rain, and November is the driest month with only 4.2 rainy days. There are 90.9 rainy days annually in Keystone, which is one of the rainiest places in South Dakota. The rainiest season is Autumn when it rains 34% of the time and the driest is Spring with only a 15% chance of a rainy day.

June is the rainiest month in Rapid City with 11.8 days of rain, and November is the driest month with only 4.0 rainy days. There are 85.4 rainy days annually in Rapid City, which is rainier than most places in South Dakota. The rainiest season is Autumn when it rains 34% of the time and the driest is Spring with only a 15% chance of a rainy day.

An annual snowfall of 54.1 inches in Keystone means that it is one of the snowiest places in South Dakota.

An annual snowfall of 38.0 inches in Rapid City means that it is about average compared to other places in South Dakota.

April is the snowiest month in Keystone with 12.1 inches of snow, and 9 months of the year have significant snowfall.

March is the snowiest month in Rapid City with 8.6 inches of snow, and 8 months of the year have significant snowfall.