* WHAT...Hot daytime conditions with high temperatures between 88 and 98 common, hottest Friday. Warm overnight conditions will bring less relief than usual. * WHERE...Most coastal areas of Los Angeles, Ventura, and southern Santa Barbara Counties. * WHEN...For the Extreme Heat Warning, until 8 PM PDT this evening. For the Heat Advisory, from 8 PM this evening to 8 PM PDT Saturday. * IMPACTS...There is a high risk for dangerous heat illness, especially for sensitive groups like the very young, the very old, those without air conditioning, and those active outdoors.