US natural gas futures are surging toward the biggest monthly gain on record, buoyed by scorching weather and the expiration of August options. Gas has jumped more than 65% in July. Though the outage at the Freeport export plant in Texas has stranded gas in the domestic market, the bulk of that supply has been burned for power to cool homes and businesses amid blistering temperatures. Gas demand for power generation has jumped by more than 10% this month from a year ago to record levels, according to BloombergNEF data. Booming summer gas use and muted production growth from shale basins have left stockpiles of the fuel about 12% below normal, stoking concern about supply constraints in the colder months. The so-called widowmaker spread between gas delivered in March and April — essentially a bet on how low inventories will be by the end of winter — widened to […]