* WHAT...High temperatures 100 to 105 degrees in the valleys each afternoon. * WHERE...White Pine, Northern Elko, and Ruby Mountains and East Humboldt Range in Elko Counties. * WHEN...Until 11 PM PDT Sunday. * IMPACTS...Hot temperatures may cause heat illnesses. Drink plenty of fluids, remain in an air-conditioned room, stay out of the sun, and check on relatives and neighbors.