Natural gas closed at a three-month high on speculation that cooler weather will hit the northern U.S. in the last two weeks of this month.

AccuWeather Inc. revised its forecast to show colder-than- normal air over much of the western and central U.S. from Nov. 23 through Nov. 27. The State College, Pennsylvania-based forecaster yesterday predicted warmer-than-average air over much of the country, including the northern third.

``You keep getting speculative dollars flowing in here on any news of a cold front,'' said Carl Neill, an analyst with Risk Management Inc. in Chicago.

Gas for December delivery gained 42.4 cents, or 5.5 percent, to $8.179 per million British thermal units on the New York Mercantile Exchange, the highest close since July 31. Benchmark futures are 8.6 percent higher this month. They gained 4.9 percent this week.

MDA EarthSat Energy's revised outlook today showed a shot of colder-than-average air pushing across the northern Plains and Midwest from Nov. 27 through Dec. 1.

The Midwest is the biggest gas-consuming region in the U.S. Seventy-nine percent of households there burn the fuel for heat, according to Energy Department data.

Mild Weather

Mild weather last week let utilities add to the underground caverns that hold excess supplies. U.S. gas inventories rose 5 billion cubic feet to 3.45 trillion last week, the Energy Department reported yesterday. The increase was the first in three weeks and left stockpiles the highest they've ever been at this time of the year.

``Warmer weather across all major U.S. natural gas markets likely undermined heating demand for natural gas in the week ending Nov. 10, causing underground inventories to rise,'' Antoine Halff, vice president and head of energy research at Fimat USA Inc. in New York, told clients in a report on Nov. 15. ``Nuclear plants continued to boost power generation, further trimming requirements from gas-fired plants.''

Gas inventories are 7.4 percent higher than the average for the past five years and 5.4 percent above a year ago at the comparable time.

Technical traders have made several attempts this week to bring gas prices past the $8.26 three-month high from Nov. 9. Each time, they have been turned back. The closest was a price of $8.25 during today's session.

``We should fail at the same levels that we've been failing at,'' said Michael Guido, director of hedge-fund marketing at Societe Generale in New York. ``Fundamental traders are not going to buy natural gas above $8.30. It's just chart-based traders trading off numbers.''