FORT COLLINS, Colo. -- Colorado hurricane researchers are forecasting above-average hurricane activity for the month of September.

The Colorado State University forecast team said Tuesday that it predicts five tropical storms in the Atlantic this month, including four hurricanes, two of them major, as Category 3, 4, or 5.

Former Colorado State University climatologist William Gray said Tuesday that would be nearly twice as busy as an average September. Gray has been issuing hurricane forecasts at Colorado State University for 25 years.

"We predict that September will be quite active based on climate signals through August," said Gray.

"We have seen some of the lowest pressure readings on record in the tropical Atlantic during August. Water temperatures in the tropical Atlantic remain at above-average values. A combination of these two factors typically leads to an active September," said Phil Klotzbach, lead author of the hurricane forecast.

Tropical Storm Ike, which formed Monday, and Tropical Storm Josephine, which formed Tuesday, count toward the five storms in the September forecast, said Klotzbach.

Klotzbach said Hanna, which reached hurricane strength on Monday before weakening to a tropical storm on Tuesday, counts toward the four hurricanes. As a tropical storm, Hanna doesn't count toward the five in the September forecast because it formed in August.

Three other Atlantic hurricanes have been recorded so far this season.

June and July were very active with three named storms forming during the two-month period (Bertha, Cristobal and Dolly). Bertha became the longest-lived July storm on record, while Hurricane Dolly made landfall in south Texas as a Category 2 hurricane.

The team's latest predictions cover only September and are not a revision of its season-long forecast. The team's most recent seasonal prediction, issued Aug. 5, called for a total of nine Atlantic hurricanes during the season, which runs from June 1 to Nov. 30.