Parts of the U.S. Southwest are bracing for a second summer heat wave as a high pressure ridge rolls in to bake Arizona, California and Nevada in triple-digit temperatures. Meteorologist for the National Weather Service in Phoenix James Sawtelle says temperatures are expected to ratchet up to 111 degrees by Saturday and as high as 120 degrees on Sunday and Monday. Excessive heat warnings are in effect through the first half of the week. Arizona Department of Health Director Dr. Cara Christ is warning residents to watch for signs of heat illness: thirst, red skin, cramping, exhaustion and a lack of sweat. Government and industry are prepping for the heat issuing precautions and planning for the worst. A heat wave in early June brought temperatures as high as 117 degrees in Phoenix.