The weekend is over, and you probably have a bad case of the Monday blues. If so, lift your spirits by getting a jump on next weekend’s plans — which could include a free trip through one of America’s national parks.

Next Saturday — Sept. 30 — is National Public Lands Day. That means there will be no entrance fee at any of the nation’s 400 national parks on that day.

Most parks are free throughout the year, but 124 parks normally charge an entrance fee. So, to make the most of this deal, visit one of those parks on Sept. 30 and enjoy a little early fall weather.