* WHAT...Temperatures in the mid to upper 90s. Low temperatures early Thursday morning generally in the mid to upper 60s, but locally around 70. * WHERE...In Oregon, Lower Columbia, Greater Portland Metro Area and Central Willamette Valley. In Washington, I-5 Corridor in Cowlitz County and Greater Vancouver Area. * WHEN...From noon Wednesday to 10 PM PDT Thursday. * IMPACTS...Heat will increase the risk of heat-related illnesses for those who are sensitive to heat, especially those without effective cooling or adequate hydration. 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 frequent rest 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 9 1 1.