Itchy skin after sun exposure can be caused by a number of different conditions. The most common is a disorder called polymorphous light eruption (PMLE), although there are also autoimmune diseases such as lupus, dermatomyositis that can cause this, along with allergies that arise only when exposed to sun. I would suggest evaluation by a dermatologist to eliminate worrisome causes. You may also read an article published this past month in the Anacortes American newspaper, where I answered questions on this very subject. The link is here. Thanks for the question.