"There are no mitigating factors that could suppress hurricane activity," said Gerry Bell, NOAA's lead hurricane forecaster, in a conference call with reporters. "It will be active or very active."

Bell noted that water temperatures in the Atlantic are eight-tenths of a degree Fahrenheit above normal for this time of year. "That might not sound like much, but it's quite a bit," he said. (Read "Weather Gone Wild" in National Geographic magazine.)

Hurricanes draw their fierce power from warm water, and can intensify when there are no upper-level winds—known as wind shear—to disrupt their momentum.

NOAA forecasters predict that 13 to 20 named tropical storms with winds of at least 35 miles per hour (56