NWS Forecast Office Phoenix, AZ

A weather disturbance will act to increase the coverage of thunderstorms across the lower deserts later this week. Better moisture levels will overspread the region, and thunderstorm hazards are likely to transition from severe winds & dust to primarily flash flooding. The greatest coverage of showers and storms across the state is currently forecast on Wednesday and Thursday.

A weather disturbance will support increasing coverage of storms across the state, especially Wednesday and Thursday when a moist environment will allow for efficient, heavy rainfall with thunderstorms. As such, the probabilities for excessive rainfall leading to rapid onset flooding will increase.

High pressure aloft, high humidity levels, and mostly sunny skies will allow for above normal temperatures the next few days for portions of Southwest AZ and Southeast CA. Overnight lows in the 80s will be common through Thursday morning in some of the hottest areas. The high humidity will make afternoon highs feel hotter than the actual air temperatures, with Heat Indices forecast upwards of 110° to as much as 120° in the Imperial Valley. An Extreme Heat Warning will be in effect through Thursday.

High pressure over the region in combination with slight day to day variations in moisture/cloud cover will allow temperatures to fluctuate near to above normal through the middle of the week, leading to widespread Moderate HeatRisk. Practice smart heat safety by drinking plenty of water and electrolytes and reducing your time outside during the afternoons. Cooler temperatures are then expected to arrive late week as a disturbance impinges on the Desert Southwest, bringing chances for widespread rainfall and more persistent cloud cover.