NEW YORK (Dow Jones)--Natural gas futures slumped Wednesday, pressured lower by mixed weather forecasts and book-squaring ahead of the November contract expiration.

Natural gas for November delivery on the New York Mercantile Exchange settled 26.8 cents lower, or 5.9%, at $4.289 a million British thermal units after reaching a low of $4.23/MMBtu earlier in the day. The December contract, which was more heavily traded Wednesday, settled 4.1% lower at $5.066/MMBtu.

Traders were selling contracts in advance of the November contract expiration at the end of the trading day Wednesday.

"A lot of people bought this contract when prices were rising [this month], and they held on just a little too long," said Peter Beutel, the president of Cameron Hanover, a New Canaan, Conn., energy advisory firm.

Market participants were also trying to gauge whether temperatures in the major gas-consuming regions over the next two weeks would be cold enough to spark significant heating demand. Commodity Weather Group, a Bethesda, Md., private forecaster, was predicting above-normal temperatures across much of the eastern half of the U.S. from Oct. 28 to Nov. 1, with normal temperatures in New England. From Nov. 2 to Nov. 6, below-normal temperatures were expected in the Northeast, with normal temperatures elsewhere in the East, according to CWG. Warmer-than-normal temperatures were predicted for most of the contiguous U.S. in the second week of November.

"We continue to have weather model volatility, which is reducing confidence in the outlook for the first half of November," CWG meteorologists wrote in a note to clients Wednesday.

Meanwhile, gas inventories remain ample despite expectations of a smaller-than-normal build in U.S. storage for the week ended Oct. 23.

The U.S. Energy Information Administration is expected to report that 29 billion cubic feet of gas were added to storage during the week, according to the average prediction of 18 analysts and traders in a Dow Jones Newswires survey. Storage constraints have limited the amount of gas that could be added to stockpiles over the past few weeks.

The storage estimate falls short of last year's 49 bcf build in storage and the five-year average injection, which was 43 bcf. If the estimate is correct, inventories as of Oct. 9 will total 3.763 trillion cubic feet, 13% above the five-year average and 11% above last year's level.

-By Christine Buurma, Dow Jones Newswires; 713-547-9201;