Hello. Thank You For Your Assistance. My Knee Cap Keeps

hello. Thank you for your assistance. My knee cap keeps on slipping out of joint. Is this normal when moving from a warm climate to a colder, wet climate? As I walk, I feel no pain but my knee cap slips out to the left or right often and hurts when it slips out (shocking and uncomfortable pain) but doesn't hurt to walk. I am a woman 45 years of age. No prior knee injuries that required surgery. My e-mail address is YYYY@YYYY .