Portland (OR) Rainfall & Precipitation: Monthly Averages and Year-Round Insights

This page shows the average amount of rainfall per month in Portland (OR). The numbers are calculated over a 30-year period to provide a reliable average. Now, let’s break down all the details for a clearer picture.

Portland experiences significant rain/snowfall throughout the year, averaging 1050 mm of precipitation annually.

Monthly Precipitation Levels

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

The climate in Portland shows significant variation throughout the year. Expect 179 mm of precipitation during the wettest month December, distributed over 20 rainy days.

In contrast, August offers drier and sunnier days, with around 11 mm of rainfall over 3 rainy days.

December, the city’s wettest month, has a maximum daytime temperature of 7°C and receives 64 hours of sunshine. During the driest month August you can expect a temperature of 28°C. For more detailed insights into the city’s temperatures, visit our Portland 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

Portland’s average annual precipitation is 1050 mm. Let’s compare this to some popular worldwide tourist destinations:

In Lisbon, Portugal, the average annual precipitation is 774 mm, characterized by wet winters and dry summers typical of the Mediterranean climate.

In Seoul, South Korea, the average annual precipitation is 1237 mm, with most rain falling during the summer monsoon season.

Melbourne, Australia, has 690 mm of rainfall annually, spread fairly evenly throughout the year.

Singapore, situated near the equator, gets 2581 mm of rainfall annually, with no distinct dry season and consistent monthly precipitation.

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 Portland (OR)’s weather, including sunshine hours, humidity levels, and temperature data, visit our Portland (OR) Climate page.