The weather SHOULD be much warmer by the time you go, temperatures would normally be up in to at the very least the high 20's with plenty of sun and very litttle if any indeed any rain and no need for a pullover / cardigan.

Having said that have a friend who is just back from Dalyan and it rained every single day during her visit so the weather hasn't quite picked up yet.

I was looking at the forecast for you and it would appear that the weather is getting better however they predict a bit of rain not long after you arrive, then again how accurate are long range weather forecasts?

Take a look at this http://www.holiday-weather.com/icemler_/forecast/fourteen-day/

Graham