* WHAT...Dangerously hot conditions possible. Afternoon temperatures 108 to 116. Major Heat Risk.
* WHERE...In Arizona, Central La Paz, Gila River Valley, Kofa, and Southeast Yuma County. In California, Joshua Tree National Park.
* WHEN...From Thursday morning through Monday evening.
* 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.