* WHAT...Dangerously hot conditions. Afternoon temperatures 106 to 112 expected. Major Heat Risk. * WHERE...In Arizona, Parker Valley and Yuma. In California, Chuckwalla Valley, Imperial Valley, and Palo Verde Valley. * WHEN...From 11 AM MST /11 AM PDT/ to 8 PM MST /8 PM PDT/ Monday. * IMPACTS...Heat related illnesses increase significantly during extreme heat events. Overexposure can cause heat cramps and heat exhaustion to develop and, without intervention, can lead to heat stroke.