Date. Event Website. View Event. At National Today, we love celebrating 149 September holidays. Dry days in September. function fbl_init(){ August 30, Monday: Janmashtami. Visit The National Parks On These Fee-Free Days In 2021. It’s going to be even easier to visit national parks on six specific days in 2021 because the National Park Service has designated them “free days” to increase access and promote recreational opportunities. window.FB.init({ } August 10, Tuesday: Muharram.