I've been trying to keep up to date on closures and people are reporting to me on what they see on the trail. Here's what I know:
Some popular state parks are closing, including Elephant Rocks and Castlewood; here's the Post-Dispatch story. This is no surprise since both those parks were zoos over the weekend.
Two friends have gone to Bluff View in the last week and reported that it wasn't too crowded.
For an alternative to Elephant Rocks, try Hughes Mountain. It's incredible.
My family went to Mastadon State Historic Site Sunday afternoon. It was quite busy and maybe one in ten hiker groups were making an effort to keep six feet between out group and theirs. In the future I'll try to stick to weekdays or days when it's raining enough to keep the less hardy hikers inside.
Check out the web sites for county park systems as well as state parks for closures. Your best bet is always to go as early in the day as you can, go during the week, or when the weather isn't ideal.
Let me know what you find when you hike; I want to help people stay informed and hike safely.