Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors.

* WHAT...Dangerously hot conditions with daytime temperatures up to 109 degrees expected. Overnight low temperatures will offer little reprieve from the heat. * WHERE...Eastern San Fernando Valley, Santa Clarita Valley, and Western San Fernando Valley. * WHEN...Until 8 PM PDT Thursday. * IMPACTS...There is a high risk for dangerous heat illness for anyone, especially for the very young, the very old, those without air conditioning, and those active outdoors.