Weather in September
Weather of Istanbul is really calm during September. Signs of Autumn are visible, but it is still warm and enjoyable. It is not a rainy season and mean temperature is around 20 C.
You don’t need thick clothes, but you may need a raincoat to be on the safe side. Before coming you should keep looking to this [web site](http://www.
mgm. gov. tr/sondurum/turkiye. aspx? g=H&h=SH).