Watch August for hurricanes

The 2009 hurricane season is getting off to a slow start, but experts say the real activity usually doesn't begin until August.

Even though the first Atlantic named storm usually forms by July 10, the early lull doesn't necessarily mean a weak season.

Thursday was the one-year anniversary of Hurricane Dolly, which became the Rio Grande Valley's most destructive storm in four decades when it struck South Texas.

A maturing El Niño in the Pacific Ocean, which tends to depress storm activity by 20 to 40 percent, makes the outlook promising for the rest of the season.

But forecasters say it's no time to relax. El Niño years can still produce destructive storms.

The 2004 season didn't get its first storm until Hurricane Alex began developing July 31. After Alex, the season finished with 15 storms and six major hurricanes, including Hurricane Ivan.

One of the three most intense storms with a U.S. landfall, Hurricane Andrew, developed during an El Niño in 1992. Some of the most famed storms to strike Texas and Louisiana have come during an El Niño, including the great storm of 1900, said Jill Hasling, president of Houston's Weather Research Center.

"There might be fewer storms during an El Niño," she told the Houston Chronicle. "But it only takes one."

This year's outlook

Ten tropical storms or hurricanes develop during an average Atlantic season, but since 1995, the Atlantic has seen an upswing in activity. Most scientists attribute that to a long-term natural pattern.

Given this season's slow start and the onset of El Niño, most seasonal forecasters now say about 10 named storms will form, one of the lowest totals of the past 15 years.

The Atlantic hurricane season runs from June 1 to Nov. 30.