It is a nice route through Oregon and make sure you stop at John Day Fossil Beds with your camera loaded. Also a tour of the Chinese Doctors museum in town is well worth the trip. I would think the weather would be find but if it isn't, not a big deal if you cut over to 97 on either 26 or further south on 20. If you haven't seen Crater Lake, it is worth the side trip.
Just in case I would buy some chains, as around Mammoth Lakes it might get crazy. We are going later in the year and our alternate plan is to take Hwy 50 to Nv 95 to 6 and back to Bishop and 395. While it looks a lot longer, according it google maps its only about 20 minutes longer as straight.
