Magnuson Series Earth Day Half Marathon, 10K & 5K

Saturday, April 20, 2024 • Seattle, WA • Course Map

Part of a series of running and walking events that take place throughout the summer and fall seasons in Seattle’s Magnuson Park, which lies right on the shores of Lake Washington, the Magnuson Series Earth Day race features five race distances — a half marathon, 10K, 5K and a dash run for kids.

The April Earth Day race is one of a dozen planned races in the series, which takes place once each month from January through November, all of which will follow the same race routes around the winding park roads and trails inside Magnuson Park, to give runners a chance to gauge the progress of their improvement in their fitness levels over the course of the second half of the year.

Organized by Club Northwest, a locally based running club, the events all use the same 5-kilometer course as the baseline route from which all the other events are built upon.

Those running the 5K on the day of the race, for example, run the route a single time, while those running the 10K run it twice, those running the 15k run it three times, and those running the half marathon make three loops around the course, plus an additional one-kilometer stretch near the start & finish line area.

All races start and finish near the parking lot area on the western side of the park, which lies along the mile-long stretch of the Lake Washington shoreline.

From there, runners follow a counter-clockwise loop along the roads and trails that wind through this 350-acre park, past the wide-open fields, athletic facilities and past the buildings that once serve as the military headquarters for the naval air station that occupied the land the park now sits on, back in the 1940s.

Race Weather & Climate

Located in northwestern Washington on the ithsmus of land that lies between Lake Washington and Puget Sound, Seattle typically sees cool to mild weather in April, which has brought record temperatures here as low as 32°F (in 1997) and as high as 85°F (in 1976).

On race day (April 20), the average low is 43ºF and the average high is 59ºF.

Past Results

Course Map

See the race route map for the Magnuson Series Earth Day Half Marathon here.

Starting Time

10:00 AM


See race website


To reserve your spot in the 2024 running of Seattle’s Magnuson Series Earth Day Half Marathon, 10K or 5K race, register online at the event website here.

Official Race Website


Ever run in the Magnuson Earth Day Half Marathon? Share your impressions here, or post your review in the Comments below.

See more races in: April, Washington

1 comment… add one
  • Dayanna March 17, 2020, 4:22 pm

    Is this half marathon still taking place on April 18th?


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