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

This page shows the average amount of rainfall per month in Lake Oswego (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.

Lake Oswego is known for its substantial rain/snowfall, with annual precipitation reaching 1155 mm.

Monthly Precipitation Levels

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

The seasons in Lake Oswego, bring significant changes in precipitation. The wettest month, December, receives heavy rainfall, with an average of 193 mm of precipitation.

This rainfall is distributed across 21 rainy days. In contrast, the driest month, July, experiences much less rainfall, totaling 11 mm over 4 rainy days. These distinct seasonal differences provide diverse experiences throughout the year.

December, the city’s wettest month, has a maximum daytime temperature of 8°C. During the driest month July you can expect a temperature of 28°C. For more detailed insights into the city’s temperatures, visit our Lake Oswego 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

Lake Oswego’s average annual precipitation is 1155 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.

Perth, Australia, receives 565 mm of rainfall annually, mostly during the winter months.

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

• "Ginger" was the longest-lasting Atlantic tropical storm, which spun around the open ocean for 28 days in 1971.
• The world's largest snowflake was recorded in the Guinness Book of Records, at 38 cm wide and 20 cm thick. The snowflake fell at Fort Keogh, Montana, USA, on 28 January 1887.
• The greatest snowfall recorded was on Mt. Rainier, Washington State, USA—over 31.5 meters fell during the winter of 1972.

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