 128 million people in the U.S. are under heat alerts, and there are excessive heat warnings in cities like Philadelphia and Baltimore. Record heat also expected in the West, and ABC medical correspondent Dr. Darian Sutton says there are ways to make sure kids are staying safe this summer. This summer is expected to be one of the hottest summers on record, so making sure you remember that children are also susceptible to heat-related illness. We're talking about heat stroke and heat exhaustion, and the number one way to prevent that is with hydration.