Mercer Island (WA) Rainfall & Precipitation: Monthly Averages and Year-Round Insights

This page shows the average amount of rainfall per month in Mercer Island (WA). The numbers are calculated over a 30-year period to provide a reliable average. Let’s explore the details in depth to provide you with a complete overview.

Mercer Island is known for its substantial rain/snowfall, with annual precipitation reaching 1045 mm.

Monthly Precipitation Levels

The average number of days each month with precipitation (> 0.2 mm)

The climate in Mercer Island shows significant variation throughout the year. Expect 168 mm of precipitation during the wettest month November, distributed over 21 rainy days.

In contrast, July offers drier and sunnier days, with around 15 mm of rainfall over 4 rainy days.

November, the city’s wettest month, has a maximum daytime temperature of 11°C and receives 73 hours of sunshine. During the driest month July you can expect a temperature of 25°C. For more detailed insights into the city’s temperatures, visit our Mercer Island Temperature page.

Annual Precipitation in the United States of America

The map below shows the annual precipitation across the United States of America. You can also select the different months in case you are interested in a specific month.

Amsterdam Precipitation Compared World Wide

Mercer Island’s average annual precipitation is 1045 mm. Let’s compare this to some popular worldwide tourist destinations:

Chicago, USA, sees an annual precipitation of 1062 mm, with rain and snow contributing to its humid climate.

Meanwhile, Buenos Aires, Argentina, enjoys a humid subtropical climate with 1000 mm of annual rainfall, mostly in the summer.

In Tokyo, Japan, the average annual precipitation is 1528 mm, with significant summer rains due to typhoon season.

Bangkok, Thailand, experiences a tropical monsoon climate with 1668 mm of annual rainfall, with the heaviest precipitation occurring during September and October.

How is Precipitation Measured?

Precipitation amounts are measured using specific gauges installed at weather stations, collecting both rain and snow and any other type of precipitation. Rainfall is measured directly in millimeters, while that from snow and ice is obtained by melting it. Automated systems often incorporate heaters to make this easier.

Information from these stations is transmitted via Wi-Fi, satellite, GPS, or telephone connections to central monitoring networks. This information is immediately updated and integrated into weather models and forecasts.

Interesting weather facts

• The U.S. has a significant number of thunderstorms every year, with over 14.6 million taking place across the world annually.
• Approximately 70% of lightning bolts strike land rather than oceans.
• A storm named John was the longest-lasting Pacific tropical storm, continuing for 31 days. As it crossed the dateline twice, it changed status from a hurricane to a typhoon and back to a hurricane.

For more detailed information about Mercer Island (WA)’s weather, including sunshine hours, humidity levels, and temperature data, visit our Mercer Island (WA) Climate page.