Added 2021-09-16
If you are on your way into the park to see Old Faithful or the Upper Geyser Basin, you should stop and see these falls. You can see the waterfall from the main road, but it's a short trail to get a front-row seat.
Right off the road on U.S. Highway 191 is a slight pull-off where you can park before the trailhead (indicated by attached GPS coordinates).
The trail is open when the park is, but it can be hard to follow in the winter if it's covered in snow.