With snowmen built up this week in the Midwest and Northeast melting into nothing but a puddle of water amid a rise in temperatures, spot natural gas prices disintegrated during the Oct. 17-21 trading period. NGI’s Weekly Spot Gas National Avg. plunged 54.0 cents to $4.985/MMBtu.

Perhaps in an even bigger reflection of the overarching bearishness in the gas market, Nymex natural gas futures staged a six-day sell-off that left the November contract below $5 at the end of the week. The prompt month settled Friday at $4.959, off 39.9 cents from Thursday’s close and off $1.494 from a week earlier (Oct. 14).

West Coast locations were among the biggest cash movers this week as late-season heat finally dissipated and crisp autumn air arrived. In the Rockies, Kingsgate spot gas...