2025 Compare Climate & Weather:
Oak Harbor, WA vs Mercer Island, WA

Highlights

On average, there are 156 sunny days per year in Mercer Island. Oak Harbor averages 159 sunny days per year. The US average is 205 sunny days.

Mercer Island, Washington gets 39.2 inches of rain, on average, per year. Oak Harbor, Washington gets 20.3 inches of rain, on average, per year. The US average is 38.1 inches of rain per year.

Mercer Island averages 5.1 inches of snow per year. Oak Harbor averages 3.8 inches of snow per year. The US average is 27.8 inches of snow per year.

Weather Highlights

Mercer Island, Washington
Summer High: the July high is around 76 degrees
Winter Low: the January low is 37
Rain: averages 39.2 inches of rain a year
Snow: averages 5.1 inches of snow a year

Oak Harbor, Washington
Summer High: the July high is around 70.4 degrees
Winter Low: the January low is 37.2
Rain: averages 20.3 inches of rain a year
Snow: averages 3.8 inches of snow a year

BestPlaces Comfort Index

The annual BestPlaces Comfort Index for Mercer Island is 7.5 (10=best), which means it is one of the most pleasant places in Washington.

The annual BestPlaces Comfort Index for Oak Harbor is 7.3 (10=best), which means it is more comfortable than most places in Washington.

Today's Weather - Oak Harbor, WA

47°F

Today's Weather - Mercer Island, WA

48°F

Average Monthly High / Low (°F)

Hot, Freezing, Rainy, Snowy Days: Oak Harbor / Mercer Island

August is the hottest month for Oak Harbor with an average high temperature of 71.2°, which ranks it as one of the coolest places in Washington. In Oak Harbor, there are 2 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Oak Harbor are August, July and September.

August is the hottest month for Mercer Island with an average high temperature of 76.5°, which ranks it as about average compared to other places in Washington. In Mercer Island, there are 4 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Mercer Island are August, July and September.

December has the coldest nighttime temperatures for Oak Harbor with an average of 36.0°. This is one of the warmest places in Washington.

December has the coldest nighttime temperatures for Mercer Island with an average of 35.7°. This is one of the warmest places in Washington.

In Oak Harbor, there are 0.3 days annually when the high temperature is over 90°, which is one of the coolest places in Washington.

In Mercer Island, there are 1.8 days annually when the high temperature is over 90°, which is cooler than most places in Washington.

In Oak Harbor, there are 27.9 days annually when the nighttime low temperature falls below freezing, which is one of the warmest places in Washington.

In Mercer Island, there are 25.4 days annually when the nighttime low temperature falls below freezing, which is one of the warmest places in Washington.

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

November is the wettest month in Oak Harbor with 3.1 inches of rain, and the driest month is July with 0.8 inches. The wettest season is Spring with 31% of yearly precipitation and 14% occurs in Autumn, which is the driest season. The annual rainfall of 20.3 inches in Oak Harbor means that it is drier than most places in Washington.


November is the wettest month in Mercer Island with 6.3 inches of rain, and the driest month is July with 0.9 inches. The wettest season is Spring with 39% of yearly precipitation and 9% occurs in Autumn, which is the driest season. The annual rainfall of 39.2 inches in Mercer Island means that it is about average compared to other places in Washington.

November is the rainiest month in Oak Harbor with 17.0 days of rain, and August is the driest month with only 5.0 rainy days. There are 138.6 rainy days annually in Oak Harbor, which is less rainy than most places in Washington. The rainiest season is Spring when it rains 32% of the time and the driest is Autumn with only a 14% chance of a rainy day.

November is the rainiest month in Mercer Island with 18.5 days of rain, and August is the driest month with only 5.0 rainy days. There are 152.7 rainy days annually in Mercer Island, which is about average compared to other places in Washington. The rainiest season is Spring when it rains 33% of the time and the driest is Autumn with only a 13% chance of a rainy day.

An annual snowfall of 3.8 inches in Oak Harbor means that it is less snowy than most places in Washington.

An annual snowfall of 5.1 inches in Mercer Island means that it is about average compared to other places in Washington.

December is the snowiest month in Oak Harbor with 1.3 inches of snow, and 4 months of the year have significant snowfall.

December is the snowiest month in Mercer Island with 2.2 inches of snow, and 4 months of the year have significant snowfall.