* WHAT...Dangerously hot conditions. Afternoon temperatures 109 to 116. Major Heat Risk.
* WHERE...In Arizona, Parker Valley and Yuma. In California, Chuckwalla Valley, Imperial Valley, and Palo Verde Valley.
* WHEN...Until 8 PM MST /8 PM PDT/ Wednesday.
* 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.