The glorious sunny weather that Lotty captured down at Olu Deniz on the web cams was a really pleasant surprise for us.
I remember a couple of days of sunshine where it was actually uncomfortable to sit in it, it was burning through my jeans! But the contrast between moving from sunny spot to shade is quite marked in the winter. Hot in one and really quite chilly in the other.
I do know that the locals have said it hasn't been a 'normal winter' - nowhere near enough rain but we witnessed many a good storm the first week we there mid January.
The problems of cold are very much down to how well your house is insulated and of course its location. The hotel we stayed in in Calis for the first week felt bitterly cold at night despite having a full house of guests and a central heating system available (we all complained to no avail). So we were really nervous about moving into our house halfway up the mountain in Ovacik the following week!
However, because the house has some decent insulation, it was warmed quite easily with the air con turned on heat mode.
The point of this laborious post (sorry) is really to say - go to the Fethiye region in winter - it really is quite beautiful in a very different way to the in season months. However, expect mixed weather and check your accommodation will be warm enough.
For me, visiting a deserted Olu Deniz was worth any cold rain. And a couple of the front line cafes stay open to serve hot drinks and Efes.