Doors opened at 10 a.m. at the "Heat of the Day Respite Center" at the Phoenix Convention Center. The center will be open through June 1.
"This is the best response the Valley has had to heat in years and it will save lives," said Wendy Johnson, executive director of the Arizona Justice Center.
Tables and chairs have been arranged to follow social-distancing guidelines amid COVID-19.
Water is being provided and St. Vincent de Paul is providing meals.
No personal belongings are being allowed inside the center, which will be cleaned overnight.
Buses will pick up people who are staying at the human services campus on Ninth Avenue and Jefferson and those buses will make stops at the campus every hour.
In order to get onto the bus, you will need a valid human services campus ID card.
"Here, we will average 20 people a day at least and then we serve lunch and then adding a dinner, so that they don't have to be tracking around the community in the heat," Johnson said. "We're putting in an event tent with coolers so that people can stay in shade, reduce their body temperature, get services they need because we offer showers. We have nursing. We have identity recovery and housing specialists."