0924 ET - U.S. natural gas futures are slightly lower as traders return from the Labor Day holiday and look toward the gradual loss of cooling demand. "The summer will transition rapidly into fall," Eli Rubin of EBW Analytics says in a note. Even meteorologists estimating cooling demand gains over the holiday weekend acknowledge cooler weather in the 11-15 day window, he adds. The regional breakdown for late September weather is "mildly supportive" for gas prices with late-season cooling demand in the South Central region and early heating demand in the upper Midwest and New England, he adds. Nymex natural gas is off 0.4% at $2.963/mmBtu.