Well I have never stayed in Marmaris but i know Bodrum is lovely in October and Marmaris isn't far from there. I have always been able to lay on the beach or swim and get a tan. It may get a bit chilly in the evenings but the days are mostly very warm.

we were in Dalyan till Nove 10th, weather was beautiful, i love Oct just nice still able to sunbathe my fav time of year as you can go see the sights and not get all hot aand bothered.

We were in Icmeler last year for 2 weeks from the 3rd October and only had one cloudy day with a shower of rain.The rest of the time was warm and sunny.It was warm on an evening too.The previous week had had a couple of days of thunderstorms.
I am going back this year in October.

We were in Marmaris for half term last year which was the last week in October. The weather was lovely and sunny, fine for sunbathing and eating outside still, just a cardie or light jacket needed for the evenings. The children were happy to go in the pools but too cold for us, although the waterpark wasn't too bad in the shallower pools.

We had no rain although the year before my parents had a couple of bad days at the same time at Lara beach. The end of October signals the closure of alot of the bars and trips in Marmaris and some were already shut for the Winter. We were able to get some bargain priced excursions though because of this.