I can't speak specifically to Mt. Adams or St. Helens, but in the North Cascades every campground, parking lot, trail head and road side scenic look out inside the park were taped off and signed as closed. The National Forest trail heads were open, although the bathrooms were locked and signed as closed. I wonder if the Cold Springs trail head would be accessible though, as there was two feet of snow at ~6,000 ft in the North Cascades.