This morning, you left the house and you had perfect hair. Then humidity kicked in and soon enough, you see frizz. Eep! Just grab some clear mascara and swipe over the frizz. That will keep your hair calm for the rest of the day. DO NOT use any water on your hair since it will only increase frizziness and make more of a mess.
P.S. If you have frizz-prone hair, avoid buying products with lanolin oil, which increases frizz and citric acid, which further dries out hair.