Excessive heat warning in effect for Inland Empire

An excessive heat warning is in effect for the San Bernardino and Riverside County Valleys until 9 p.m. Thursday as scorching temperatures remain in the Inland Empire, the National Weather Service said.

The warning includes the cities of Rancho Cucamonga, Ontario, Corona, Fontana, San Bernardino, Riverside, and Moreno Valley. Residents in these areas are urged to prepare for dangerously hot conditions with high temperatures ranging from 98 to107 degrees Fahrenheit.

"With really bad heat stroke you can have core temperatures reaching 106 degrees," said Dr. Brian Savino, an emergency room physician at Loma Linda University Health. "You have to rapidly get those patients cooled off to preserve their brain."

The National Weather Service is warning residents in the area of the potential for significant heat-related illnesses during extreme heat, when hiking and outdoor exercise activities can be deadly. Experts recommend staying hydrated, avoiding prolonged sun exposure, and using air-conditioned spaces.

Additionally, officials warned residents against leaving young children and pets in unattended vehicles.

(This is a developing story. Check back for updates.)