Is it permissible for a woman to wear a tall hat?
If she wears it for the purpose of adornment among other women or her mahram relatives, that is subject to the condition that it should not resemble the dress of men or of kaafir women. But if she goes out wearing it in front of non-mahram men, this is a kind of tabarruj (wanton display), and Allaah says (interpretation of the meaning):
“and do not display yourselves like that of the times of ignorance”
“Everything which involves wanton display or makes a woman stand out among other women in a manner that involves beautification is haraam and is not permissible for her.”