 about 60 to 90 ounces a day. Eating a proper diet can also go a long way, and avoiding strenuous activity during the hottest part of the day from about noon to 3 p.m. is a smart idea. She encourages everyone to apply sunscreen to protect their skin and check in often on people who are older or medically vulnerable, as well as pets. Donna O'Shea with UnitedHealthcare says for those who do experience heat-related illness or injuries, a virtual doctor visit can be the first step in assessing what types of care will be needed.