Natural-gas futures traded nearly flat Wednesday as traders weighed some updated weather forecasts ahead of the August contract's expiration.

Natural gas for August delivery recently traded down 0.5 cent, or 0.1%, to $4.365 per million British thermal units on the New York Mercantile Exchange. This contract expires at the end of Wednesday's session.

The most actively traded contract, for September delivery, recently traded down 0.8 cent, or 0.2%, to $4.323.

Futures rose early in the session, surpassing Tuesday's intraday highs for both of the contracts, before falling back.

The market was seeing some buying interest after a couple of weaker days, said Matt Smith, an analyst with Summit Energy in Louisville, Ky.

Some tropical activity is "providing some support, as is present warmer-than-normal conditions," he said.

Still, prices were being affected by the thinly traded August contract's expiration day as traders got out of positions.

"What's being reflected here is who wants to take delivery," said Ed Kennedy, a senior vice president of energy at INTL Hencorp Futures in Miami, Fla.

Kennedy said the market could still rally Wednesday.

The contract is expected to have a steady finish, said Jim Ritterbusch, head of trading advisory firm Ritterbusch & Associates, in a client note.

His firm noted that "this week's discounts in August futures against the physical market as favoring a relatively strong expiry."

Above-normal heat supportive of prices remains in the Midwest this week, and by next week the highest temperatures should be in Texas and the Southern Plains, MDA EarthSat Weather said. The Northeast and Mid-Atlantic regions will also see more above-normal temperatures, but cooling is likely later in the six- to 10-day forecast.

A weather system moving west-northwest near the Yucatan Channel now has an 80% chance to develop into a tropical cyclone in the next 48 hours. A tropical depression could develop later Wednesday, the National Weather Service said.

Private forecaster Commodity Weather Group predicts the disturbance could bring cooling rains to far eastern Texas by Friday, which would be a relief from the heat there.

Traders keep an eye on tropical activity as storms can hamper production in the Gulf of Mexico and affect demand in the region.

Traders are also looking ahead to Thursday's storage data from the U.S. Energy Department, expected to be smaller than recent injections because of last week's heat wave.

Last year, 31 billion cubic feet of natural gas was added to storage for the week.

"I think we need to see something below last year's number to really drive prices," Smith said.

Natural gas for next-day delivery at the benchmark Henry Hub in Louisiana recently traded at $4.46/MMBtu, according to IntercontinentalExchange, up 3.4 cents from Tuesday's average. Natural gas for Thursday delivery at Transcontinental Zone 6 in New York traded at $5.00/MMBtu, up 11.4 cents from Tuesday.