Is one allowed to wear a baseball cap on Shabbos?
Is one allowed to wear a baseball cap or the like on Shabbos if he is wearing it specifically to give shade or protect him from the rain?
If the brim is less than 3.15 inches it’s allowed (although it could be that it’s not fitting for the spirit of Shabbos). Otherwise, it shouldn’t be worn, but one shouldn’t protest those who do.
שו”ע אדה”ז שא, מח-מט.