The National Park Service offered 10 fee-free days in 2017, but nearly a third of those days are yet to come.

This fall, travelers will get three opportunities to get into national parks free of charge: on Sept. 30 for National Public Lands Day, and on Nov. 11 and 12 for Veterans Day weekend. On those days, all entrance fees will be waived, though camping and other fees will still apply.

The fee-free days apply to the 124 national parks that normally charge visitors, including Crater Lake National Park, and Lewis and Clark National Historical Park in Oregon; Olympic National Park, Mount Rainier National Park and Fort Vancouver National Historic Site in Washington; and Yellowstone, Grand Teton and Glacier National Parks around the region.

With fall foliage turning in September, and snow falling in the higher reaches of Pacific Northwest parks in November, it's a great opportunity to see some of the nation's most awesome sites in a different light.

It's also a good time to go if you're averse to crowds. For example, only about 10,000 people visited Crater Lake last November, according to park service statistics, compared with nearly 200,000 people in July.

But before you go, be sure to call or check park websites for seasonal closures, which in most cases will limit the areas you can explore.

Washington state parks also offer fee-free days, waiving the need to purchase or display a Discover Pass in parking areas. The parks department offered 12 such days in 2017, with three left to go including a new occasion, Autumn Day, on Nov. 24.

Oregon state parks do not offer fee-free days, as the vast majority of parks in Oregon are free year-round.

--Jamie Hale | jhale@oregonian.com | @HaleJamesB