The heat advisory comes during the first official day of summer. Temperatures in the area started out in the 90s and quickly rose to the triple digits, hitting 102 degrees by 4:00 p.m.
Kids like 8-year-old Gianna kept cool at the Meadow Homes Spray Park in Concord.
"My feet are burning even though we've been out here for 20 minutes," Gianna said.
Jon Searcy brought his two kids to the spray park. While the water provided a source of relief, he said, his family would seek shade indoors later during the peak of the heat.
"Thankfully my kids think fruit is like candy, so we eat a lot of fruit and water," he said.
At Concord Community Park, children took swim lessons before it got too hot outside. Lifeguard Jocelyn Ruiz said children who take classes at the pool are given 15-minute breaks. They also make sure children stay hydrated and apply sunscreen throughout the session.
She offered the following tips to anyone who will be outside during the heat advisory for the next few days.
"Bring sunscreen, bring hats, sunglasses, umbrellas… anything you can," Ruiz said. "What usually helps is to get a towel, get it wet and drape that over your shoulders. It’s good for keeping cool."
Contra Costa County Health Officials said even short amounts of time in high temperatures can pose a threat to your health. They advise people to stay indoors if possible, and to drink water in order to reduce the risk of heat exhaustion or heat stroke.