Natural gas futures rose to a three- week high in New York as forecasts showed a resurgence of hot weather in the eastern U.S. that would boost power demand. Temperatures may be higher than average on the East Coast, parts of the Gulf Coast and the Great Lakes region Aug. 21 through Aug. 25 after mild weather earlier in the month, according to MDA Weather Services in Gaithersburg, Md. The high in Philadelphia on Aug.