Call the rangers station. Bring the axe for the last bit to the crater rim; there might be a little ice left up there. And if there is, it is not going to be stable. STAY OFF THE CORNICES!! If you go into the crater, you won't come out.
Mid August = slog over wormy lava flows.
http://www.fs.fed.us/gpnf/recreation/current-conditions/msh-climbing-report.shtml
Hope you have your permits already, otherwise you can usually find them on CL