September is a nice time to go, it will still be busy although not quite as busy as July. The weather is still good too, though if you are going end of September the nights can get a little bit cooler.

Hi,

I've been at to Olu Deniz at the beginning of October before and i must say it was lovely, most day were 28/29/30 even 34 on one day, nights can be a little chilly but i think it only feels like that because it can get very hot still in the day.
You might get the odd rain shower or thunderstorm but these are generally very brief and are quite refreshing to be honest.

If you are up in Hisaronou then it can feel a little cooler at night with maybe just a very light jumper or something but i doub't you will need it. Most of the time, be it day or night i was still in shorts and t-shirt.

Looking forward to going back again later in the year myself.

Cheers

olu deniz is great around the middle of october as you have the world air games and alot of other festivals happening

Sorry Maverick, but OP asked about weather in September!

Sorry miss a bit the weather is also nice during the day and a little more comfortable at night

I was in Oludeniz the last few days of August and the first week or so of September last year and the weather was spot on. Hot but not unbearable, and cooled off a bit at night although still easily warm enough for shorts.

The resort was busy with plenty of life but obviously not quite as hectic as in peak season. Plenty of sunloungers available on the beach and at the Lagoon.