Home / States National parks in Washington Washington has 3 national parks and 6 other busy National Park System sites in this guide. The best months below balance mild weather and crowds.
Park Best months Busiest July high / January low °F Visitors a year Olympic National Park Apr, May and Jun Aug 74° / 33° 3,416,000 Mount Rainier National Park Jul, Aug and Sep Jul 62° / 24° 1,643,000 North Cascades National Park May, Jun and Sep Jul 78° / 32° 35,000 Lake Roosevelt National Recreation Area Apr, Jun and Sep Jul 82° / 19° 1,139,000 Fort Vancouver National Historic Site Apr, Jun and Sep Jul 81° / 34° 1,016,000 Ross Lake National Recreation Area Apr, May and Aug Jul 79° / 30° 1,009,000 San Juan Island National Historical Park Jun, Aug and Sep Jul 69° / 38° 428,000 Manhattan Project National Historical Park May, Oct and Nov Jul 88° / 28° 64,000 Whitman Mission National Historic Site Jun and Oct May 90° / 27° 54,000
Washington parks by month
Month Visitors, all 9 sites Sites with mild weather January 234,000 none February 267,000 none March 360,000 none April 429,000 Olympic , North Cascades , Lake Roosevelt National Recreation Area , Fort Vancouver National Historic Site , Ross Lake National Recreation Area May 820,000 Olympic , North Cascades , Fort Vancouver National Historic Site , Ross Lake National Recreation Area , Manhattan Project National Historical Park June 1,135,000 Olympic , North Cascades , Lake Roosevelt National Recreation Area , Fort Vancouver National Historic Site , Ross Lake National Recreation Area , San Juan Island National Historical Park , Whitman Mission National Historic Site July 1,630,000 Olympic , Mount Rainier , North Cascades , Ross Lake National Recreation Area , San Juan Island National Historical Park August 1,483,000 Olympic , Mount Rainier , North Cascades , Ross Lake National Recreation Area , San Juan Island National Historical Park September 1,068,000 Olympic , Mount Rainier , North Cascades , Lake Roosevelt National Recreation Area , Fort Vancouver National Historic Site , Ross Lake National Recreation Area , San Juan Island National Historical Park October 751,000 Manhattan Project National Historical Park , Whitman Mission National Historic Site November 389,000 Manhattan Project National Historical Park December 239,000 none
Weather 1991–2020 NOAA normals at each park's nearest station. Visitors National Park Service recreation visits, 2023–2025 average. Mild means an average high of 55–80°F without above-normal rain.