2025 Compare Climate & Weather:
Grand Isle, LA vs Summerville, SC

Highlights

On average, there are 209 sunny days per year in Summerville. Grand Isle averages 223 sunny days per year. The US average is 205 sunny days.

Summerville, South Carolina gets 51 inches of rain, on average, per year. Grand Isle, Louisiana gets 61.9 inches of rain, on average, per year. The US average is 38.1 inches of rain per year.

Summerville averages 0.7 inches of snow per year. Grand Isle averages 0 inches of snow per year. The US average is 27.8 inches of snow per year.

Weather Highlights

Summerville, South Carolina
Summer High: the July high is around 91.5 degrees
Winter Low: the January low is 34.6
Rain: averages 51 inches of rain a year
Snow: averages 0.7 inches of snow a year

Grand Isle, Louisiana
Summer High: the July high is around 89.4 degrees
Winter Low: the January low is 44.8
Rain: averages 61.9 inches of rain a year
Snow: averages 0 inches of snow a year

BestPlaces Comfort Index

The annual BestPlaces Comfort Index for Summerville is 7.3 (10=best), which means it is less comfortable than most places in South Carolina.

The annual BestPlaces Comfort Index for Grand Isle is 7.0 (10=best), which means it is more comfortable than most places in Louisiana.

Today's Weather - Grand Isle, LA

68°F

Today's Weather - Summerville, SC

63°F

Average Monthly High / Low (°F)

Hot, Freezing, Rainy, Snowy Days: Grand Isle / Summerville

August is the hottest month for Grand Isle with an average high temperature of 89.6°, which ranks it as one of the coolest places in Louisiana. In Grand Isle, there are 5 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Grand Isle are April, October and May.

July is the hottest month for Summerville with an average high temperature of 91.5°, which ranks it as warmer than most places in South Carolina. In Summerville, there are 3 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Summerville are October, April and May.

January has the coldest nighttime temperatures for Grand Isle with an average of 44.8°. This is one of the warmest places in Louisiana.

January has the coldest nighttime temperatures for Summerville with an average of 34.6°. This is warmer than most places in South Carolina.

In Grand Isle, there are 41.0 days annually when the high temperature is over 90°, which is one of the coolest places in Louisiana.

In Summerville, there are 60.7 days annually when the high temperature is over 90°, which is hotter than most places in South Carolina.

In Grand Isle, there are 5.7 days annually when the nighttime low temperature falls below freezing, which is one of the warmest places in Louisiana.

In Summerville, there are 39.8 days annually when the nighttime low temperature falls below freezing, which is warmer than most places in South Carolina.

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

In Summerville, 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.

July is the wettest month in Grand Isle with 7.7 inches of rain, and the driest month is November with 3.6 inches. The wettest season is Autumn with 34% of yearly precipitation and 20% occurs in Summer, which is the driest season. The annual rainfall of 61.9 inches in Grand Isle means that it is wetter than most places in Louisiana.


August is the wettest month in Summerville with 6.7 inches of rain, and the driest month is November with 2.8 inches. The wettest season is Autumn with 36% of yearly precipitation and 20% occurs in Summer, which is the driest season. The annual rainfall of 51.0 inches in Summerville means that it is wetter than most places in South Carolina.

July is the rainiest month in Grand Isle with 12.7 days of rain, and April is the driest month with only 4.8 rainy days. There are 100.2 rainy days annually in Grand Isle, which is about average compared to other places in Louisiana. The rainiest season is Autumn when it rains 36% of the time and the driest is Summer with only a 18% chance of a rainy day.

August is the rainiest month in Summerville with 12.3 days of rain, and November is the driest month with only 6.7 rainy days. There are 103.7 rainy days annually in Summerville, which is about average compared to other places in South Carolina. The rainiest season is Autumn when it rains 33% of the time and the driest is Summer with only a 21% chance of a rainy day.

There is rarely any recorded snowfall in Grand Isle, ranking it as one of the least snowy places in Louisiana.

An annual snowfall of 0.7 inches in Summerville means that it is about average compared to other places in South Carolina.

Any measurable snowfall is a rare occurance in Grand Isle.

December is the snowiest month in Summerville with 0.3 inches of snow, and no months of the year have significant snowfall.