The Bay Area is heating up to dangerous levels as the week begins. An excessive heat warning is in effect through Thursday evening. Ten cities set heat records yesterday and the region will be broiling under daytime temperatures from 102 to 110 the next four days. Santa Rosa reached 106 degrees, Healdsburg was 110, Petaluma hit 102 degrees: all record breakers. Officials warn that temperatures that hot, combined with high humidity can trigger heat illness very quickly. They say drink plenty of fluids, stay out of the sun as much as possible, stick close to air conditioning, and check on neighbors and relative