After another surprising rally at the end of last week, natural gas futures tapped the brakes Monday as traders appeared less confident in avoiding a storage inventory crunch ahead of winter. The September Nymex gas futures contract hit a $2.396 intraday high before settling the day at $2.339, off 1.7 cents from Friday’s close. October slipped 1.9 cents to $2.476.

Evening markets

Spot gas prices were mostly higher, and especially in California, where sweltering temperatures led to rolling blackouts over the weekend and the power grid remained at risk given persistently hot forecasts. Led by a massive $6.600 gain in Southern California, NGI’s Spot Gas National Avg. jumped 32.5 cents to $2.530.

On the Nymex futures front, although prices started out the day a few cents slightly higher,...