FORT LAUDERDALE, Fla. -- Hurricane season might seem to have been pretty tame so far, particularly in light of the predictions for a highly active year.

Through the first seven weeks, a hurricane and two tropical storms have emerged, about average activity.

But the meanest stretch -- the seven weeks from mid-August through early October -- is here, and "now the game starts," said Stanley Goldenberg, a research meteorologist with the National Oceanic and Atmospheric Administration.

Water in the tropical Atlantic is heating up. The atmosphere in the deep tropics is becoming more moist. The upper-level winds are easing. And more robust tropical waves are rolling off the coast of Africa.

Possibly adding fuel, La Nina, the large-scale atmospheric force that promotes storm formation, is kicking in, experts said.

As a result, forecasters predict 18 to 20 named storms, including 10 to 12 hurricanes, will develop yet this season.

They project five or six will be intense, with winds greater than 110 mph.

An average season sees 11 named storms, including six hurricanes, two intense.

Goldenberg said several seasons have started slow or average and ended up being extremely active.

"People say in August, it sure seems quiet," said Goldenberg, who works for NOAA's Hurricane Research Division in Miami.

"I say just wait, the season hasn't really gotten started."

He also noted that in highly active seasons, there is a 90 percent chance that at least one hurricane will strike the East Coast.

Just the same, forecasters expected more activity in June and July, and noted that unexpected levels of wind shear, dry air and Saharan dust acted to subdue systems.

Phil Klotzbach, a Colorado State University climatologist, said an expansive system of low-pressure is largely responsible for creating the wind shear, but that system starts to weaken at this time of year, he said.