Just back from new year's at Thredbo in the Australian Alps. The weather was fine most days. The most popular activity in summer is walking to Mt Kosciuszko (Australia's highest mountain).
But as I had done that before, instead went up the gentle walking track beside the Thredbo River river 4 km to Deadhorse Gap. There were many wildflowers in bloom along the river. Then back up Ramshead Range and 4 km back to the chairlift at Thredbo. At this point it would have been a good idea to take the chairlift down, but instead walked.
There are what seem like thousands of stairs down the range to Thredbo village. At several points the walking track crosses the mountain bike track and you have to be careful of the cyclists coming down at breakneck speed.
There is a web cam and automated weather station on top of the chairlift. But keep in mind that conditions are generally much warmer, calmer and clearer in the valley where the village is, than on top of the range.
The village is equipped for summer and winter sports and all conveniences, including WiFi access (buy a card with time at the gift shop).
Accommodation ranges from luxury hotel style (where I stayed last time) to self catering apartments, to ski club lodges. If you are on your own or with a small group and willing to share facilities, the ski lodges are good value and good fun. The Currawong Lodge was basic but comfortable and similar to lodges I have stayed in at Charlotte Pass. You can use the central Thredbo booking system if not sure what you want, or save a few dollars and book directly with the lodge.
There are Trout in the river and you can fly fish with a licence (available for a few dollars from the chairlift shop). You can fish a few dozen steps from the bar of the hotel or find a more secluded spot. I used a $20 fishing kit I got at the supermarket in Canberra, complete with a telescopic rod and tackle box. You may want to buy a local "fly" (live bait is not permitted). Fishing is a wonderful excuse for not doing anything of the more active mountain sports.