PHOENIX (AP) — Arizona's state-run outdoor vaccination sites will switch to nighttime operations or shut down next month in anticipation of hotter temperatures, the state's top health official said Friday.

Dr. Cara Christ, director of the state Department of Health Services, said officials are already eying indoor venues with air conditioning to replace the parking lot operations at State Farm Stadium in Glendale and Phoenix Municipal Stadium. The state has already identified a site in Mesa that will replace the vaccination clinic at Chandler-Gilbert Community College.

“We know come April and May, the weather is going to be getting too warm for our volunteers and patients to be safely outside while our patients are in their cars,” Christ said.

The University of Arizona site in Tucson, however, will continue administering vaccines outdoors.

Beginning April 4, State Farm Stadium, where the NFL's Arizona Cardinals play, will only give out doses between the hours of 5 p.m. and 9 a.m. There will be more appointment times added so the capacity of doses administered daily won't won't be significantly reduced, according to Christ. She is hopeful that will only run for a short time until an indoor site is ready to open.

The state continues to add to its number of vaccination sites. Yuma Civic Center will become a state-run site on March 29 in a partnership with Yuma County and Yuma Regional Medical Center. The vaccination clinic will operate from 7 a.m. - 5 p.m. and administer 8,000 doses daily.

Arizona health officials are sticking to their current projection that those age 16 and older will be eligible to get the vaccine by May 1.

Health officials in Coconino and Pinal counties announced Friday that any county resident 18 or older will be eligible for vaccination effective immediately. Kim Musselman, Coconino County's health and human services director, said patients could end up receiving any of the three COVID-19 vaccines. Officials opened more than 2,800 appointments across the two sites, Flagstaff Medical Center and Fort Tuthill.

Coconino County also will start an “end-of-day” list for anyone who wants to be called if there are extra doses at the Fort Tuthill site.

Arizona on Friday reported 423 additional confirmed COVID-19 cases and 46 deaths while key metrics indicated continued slowing in the coronavirus outbreak.

Totals on the state's pandemic website rose to 835,030 cases and 16,691 deaths as Johns Hopkins University data indicated that seven-day rolling averages of daily new cases and daily declines declined over the past two weeks.

Meanwhile, COVID-19 hospitalizations also continued to drop, with 686 patients occupying inpatient beds as of Thursday. That's still above levels during the trough between the summer and fall-winter surges but far below the Jan. 11 high of 5,082.

The rolling average of daily new cases dropped from 1,171.6 on March 3 to 564.6 on Wednesday while the rolling average of daily deaths dropped from 62 to 26.3 during the same period.

The number of infections is thought to be far higher than reported because many people have not been tested. Studies suggest people can be infected with the virus without feeling sick.