What is appropriate and modest dress in Church. If we were invited to the White House or Buckingham Palace we would not dream for one moment to go in anything less than our best apparel. And this for a President or Queen, not Our Saviour. As Christians our clothes should always be modest, regardless whether we are male or female.
When I first went to Church in Crete I got a frightful shock, (after being used to worshipping in a monastery here), on seeing so many young women in low, low cut blouses and extremely short skirts. (My daughters told me afterwards my face was a picture, and I apparently barely raised my eyes above ground level from beginning to end of the service). Other than a very few exception the women were all bare-headed too.
As to ankle length skirts which to some seem mandatory, I recall Archbishop Nikodem of Richmond. In his last few years some loved to tease him. The mini-skirt was fashionable and they, seeking to shock him, pointed a young woman out wearing one. He quietly made plain his view that it was immodest. Then the maxi-skirt became fashionable, and remembering his previous reaction they pointed one out, expecting approval. Vladyka looked and shrugging his head, said, "Too extreme".
As a frequent visitor to Greece, I always wear a jacket to church. I also wore a jacket or light weight blazer in Southern India. Like the locals I long ago learnt to walk in the shade. Consider the Arabs, and others, who live in areas where the daytime heat is merciless. Covering up can be both modest and a comfortable response to heat as well as cold.