Mercer Island, WA Weather


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The most pleasant months of the year for Mercer Island are August, July and September. In Mercer Island, there are 4 comfortable months with high temperatures in the range of 70-85°. 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. December is the snowiest month in Mercer Island with 2.2 inches of snow, and 4 months of the year have significant snowfall. There are few days during the summer when the humidity becomes unpleasant.

Today's Weather - Mercer Island, WA

5 PM PST

Slight Chance Light Rain

58°F

7 DAY FORECASTDESCRIPTIONHIGH/LOWWIND
This AfternoonSlight Chance Light Rain59° / 49°SW 9 mph
SundayChance Light Rain58° / 50°S 8 mph
Memorial DayMostly Cloudy68° / 51°SSW 6 mph
TuesdayLight Rain Likely59° / 48°SSW 2 to 7 mph
WednesdayShowers And Thunderstorms Likely60° / 46°SW 7 mph
ThursdaySlight Chance Light Rain63° / 47°WSW 6 mph
FridayMostly Sunny68° / 51°N 6 mph

Weather Highlights

Summer High: the July high is around 76 degrees
Winter Low: the January low is 37
Rain: averages 39 inches of rain a year
Snow: averages 5 inches of snow a year


BESTPLACES COMFORT INDEX

The annual BestPlaces Comfort Index for the Mercer Island area is 9.5 (10=best), which means it is more comfortable than most places in Washington.

9.5 / 10

A higher score indicates a more comfortable year-round climate. The US average for the comfort index is 7.8. Our index is based on the total number of days annually within the comfort range of 70-80 degrees, and we also applied a penalty for days of excessive humidity.


Average Monthly High and Low (°F)
HighLow
January48° 37°
February51° 37°
March55° 40°
April59° 43°
May65° 48°
June71° 53°
July76° 57°
August77° 57°
September71° 53°
October60° 46°
November52° 40°
December46° 36°
Hot, Freezing, Rainy, Snowy Days: Mercer Island
Hot
Days
Freezing
Days
Rainy
Days
Snowy
Days
January06181
February06151
March02170
April00140
May00120
June0090
July1050
August0050
September0080
October00130
November03190
December08181

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.

Reviews for Mercer Island
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Mercer Island is a wonderful family community. It feels much more "small town" than a city even though it has a population of 20,000+. People say hello and watch out  More

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Mercer Island is a suburb of Seattle, located on an island in Lake Washington. The best thing about Mercer Island is its strategically central location relative to the  More

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Mercer Island is a suburb of Seattle, located on an island in Lake Washington. The best thing about Mercer Island is its strategically central location relative to the  More

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