Upvote:2
You will not be able to travel the Făgăraş Mountains in October. The Transfăgărăşan is closed due to snow so the only way to get up there and to Bâlea Lac (Bâlea Lake) is by the cable car.
The weather up in the Transylvania area will vary between cities and villages depending on their altitude but in cities like Braşov, Râşnov, and Sighişoara you can expect nice clear days. In other cities and towns like Sibiu, Predeal, Sinaia and Bran you can expect a rain shower (or a light snow) or two.
It is still a truly beautiful experience so enjoy your trip. Don't forget to try the ţuica.