Several years ago I took a relative to Disney who was sure she could handle the heat. Of course, as soon as we got there, she was in distress. Luckily, she had worn a gauzy shirt over her tank top and we just kept the shirt wet all day. We'd stop and get it wet, wring it out and she'd put it back on. Worked like a charm. The evaporation from the shirt provided a cooling effect on her skin. She kept her hat dampened, too.