The National Weather Service says extreme heat will arrive mid-week with the return of monsoon thunderstorm activity.

Above normal temperatures will return starting Wednesday with high temperatures in the 110-degree range and up to 116 by Friday. There is also a chance for showers and possibly thunderstorm activity for the Imperial and Yuma Valleys. Lightening, strong gusty winds and localized heavy rainfall are possible. The chance of thunderstorms is predicted with a 15 - 35 percent probability