Is Sam Houston National Forest Open for Hiking on the Weekends (site is unclear)

My wife and I want to go hiking at Sam Houston National Forest this weekend. Their site says their office is only open Monday–Friday, but it says nothing about when the park itself is open. I tried calling, but I only got to a recorded message tang didn’t provide an answer.

I’m assuming it must be open on weekends, but since it’s an hour out of town I wanted to be sure before we drive all the way out there.