I spent a week walking the Cradle Mtn-Lk St Claire Track in February. Walking the Track is by far the best way to get to the most scenic areas but in august the track is closed. you may be able to do a day walk from the southern end, after getting a boat across Lake St Claire. If not snowed in you should be able to access the Dove Lake track and possibly other tracks at the base of Cradle Mtn but whether you can actually get upto the peak is doubtful. The weather is very changeable and this winter has been cold and wet.
Good luck