From the National Weather Service:

EXCESSIVE HEAT WARNING REMAINS IN EFFECT FROM 2 PM MDT THIS AFTERNOON (Sunday, July 25th) TO MIDNIGHT MDT MONDAY NIGHT.

WHAT: Dangerously hot conditions with temperatures up to 107  expected. 

WHERE: Portions of northeast and southeast Oregon and  southwest and west central Idaho. 

WHEN: From 2 PM MDT this afternoon to midnight MDT Monday night. 

IMPACTS: Extreme heat will significantly increase the  potential for heat related illnesses, particularly for those  working or participating in outdoor activities. 

PRECAUTIONARY/PREPAREDNESS ACTIONS: Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible.

To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequentrest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 911.