Washington (AFP) – Tens of millions of Americans already baking in a scorching heat wave braced Saturday for record-setting temperatures to climb, while a major fire ravaged part of California. The country’s central and northeast regions face the brunt of the extreme temperatures, which are not expected to peak until Sunday at the earliest and have sent public health officials scrambling. More than a dozen states are under a heat advisory, with central US metropolitan areas such as Dallas and Oklahoma City expected to reach highs of over 100 degrees Fahrenheit (above 38 degrees Celsius) for at…