Arizona's first significant monsoon storm of the year is expected Saturday.
The National Weather Service has issued a hazardous weather outlook for much of the state, and expects scattered showers and thunderstorms by late morning and through the afternoon.
The weather service says warm air aloft should prevent the storm from becoming very strong and that the majority of the activity will contain moderate to briefly heavy rain and small hail.
The storm is expected to develop over the White Mountains in eastern Arizona and spread along the Mogollon Rim
The weather service also issued an excessive-heat warning for the Phoenix area, Gila Bend and Casa Grande.
Daytime highs are expected to hit between 110 and 115 degrees with overnight lows ranging from the mid-80s to near 90 degrees.