And you might even be off from work.
Bryce Canyon National Park with snow in winter season, Utah
Credit: Kryssia Campos/Getty Images

National parks are great to visit in the winter, too.

While visiting a national park may be a favorite summer getaway for some, you can experience the natural glory of the United States in the colder months as well.

On Jan. 15, Martin Luther King Jr. Day, all national parks in the United States will be totally free for visitors. If your company observes the federal holiday, what better way is there to spend a day off from work? Plus, there will only be four days in 2018 when all the parks will be free for everyone, so this is not an opportunity to be missed.

If you're busy on Martin Luther King Jr. Day, however, the three other days that the parks will be open to all are April 21 (opening of National Park Week), Sept. 22 (National Public Lands Day), and Nov. 11 (Veterans Day).

It should be noted that the free entrance days will only cover admission to the parks. Activities like camping, tours, and transportation around the park still cost extra.

Of course, these days only apply to national parks that charge a fee in the first place. There are many national park sites that are free year-round, which you can search for on the NPS website.

In August of last year, however, the lifetime pass for seniors increased in price from $10 to a whopping $80, and in May, 17 sites could see their fees raised.

All that considered, there's never been a better time to score a deal. Mark your calendars, nature lovers.