Natural-gas prices are resuming their week-long rally Monday as weather updates warmed over the weekend, signaling the potential for an uptick in demand. Natural gas for September delivery is up 8.4 cents, or 2.2%, at $3.924 a million British thermal units on the New York Mercantile Exchange. Trading for the October contract has now surpassed trading for the September contract. September options expire Tuesday and the contract expires Wednesday. The October contract rose 8.1 cents, or 2.1%, to $3.964/mmBtu. The front-month contract has gained 5.3% in a week since intraday trading on Aug. 18 dipped to nearly a nine-month low. That rally has brought gas back to the middle of a 30-cent range it has traded within for more than a month. Monday’s lift was primarily from the weather, analysts said. Weather Services International in Andover, Mass., issued a heat alert for a swath of […]