MIAMI, Aug 6 (Reuters) - The U.S. government climate agency cut its 2009 Atlantic hurricane season forecast on Thursday, predicting there would be between seven and 11 tropical storms, with three to six becoming hurricanes.

The U.S. National Oceanic and Atmospheric Administration predicted one to two of those would be "major" hurricanes of Category 3 or higher, with sustained winds of more than 110 miles per hour (177 km per hour).

The agency had predicted in May that there would be nine to 14 tropical storms, with four to seven becoming hurricanes, and one to three strengthening into major hurricanes.

The change was based mainly on the arrival of El Nino, a periodic warming of sea waters in the eastern Pacific. El Nino can dampen Atlantic hurricane activity by increasing wind shear, a difference in wind speeds at different altitudes that can tear apart nascent cyclones.