A Flex Alert was issued  and Schools across the county had minimum-day schedules Tuesday as the “unrelenting” heat wave that has sent temperatures soaring across San Diego County was expected to peak Tuesday. Record-setting temperatures are forecast in Chula Vista, Ramona and San Diego, with the high temperatures now expected to last into the end of the week, the NWS said. As a public safety measure, an excessive-heat warning for the county’s inland valleys, western foothills and deserts was extended through 10 p.m. Friday after it was initially slated to expire Wednesday.