Forecasters say the hurricane could grow as monstrous as a Category 4 storm with winds of more than 131 mph before coming ashore the U.S. mainland, as predicted, this weekend.

Hurricane Irene was a Category 2 hurricane Tuesday morning with about 100 mph winds, according to the U.S. National Hurricane Center in Miami, who expected Irene to reach Category 3 strength on Tuesday night, said spokesman Dennis Feltgen.

Officials could begin issuing watches for parts of the U.S. mainland later in the day, because the storm is so large, Florida could begin feeling some effects from the storm late Wednesday.

We want to make sure Floridians are paying attention, said Bryan Koon, director of the Florida Division of Emergency Management, who met Monday with the governor. We are at the height of the hurricane season right now. If it's not Hurricane Irene, it could be the follow-up storm that impacts us.

The last hurricane to make landfall in the U.S. was Ike, which pounded Texas in 2008, experts say.

Although, this storm is reportedly moving to the west-northwest near 10 mph, with an expected turn toward the northwest on Wednesday.

For residents in states that may be affected later this week, it's critical that you take this storm seriously, said Craig Fugate, administrator at the Federal Emergency Management Agency.

Emergency officials in North Carolina were checking pre-landfall operations to make sure equipment such as trucks, forklifts, generators and computers were working, said Ernie Seneca, spokesman for the state Department of Crime Control and Public Safety.

East Coast residents are stocking up on bottled water and plywood, and this week Hurricane Irene began trending on Twitter, with many users sharing updates on the storm's progress while others hoped it wouldn't come their way.

After several extremely active years, Florida has not been struck by a hurricane since Wilma raked across the state's south in October 2005, which was responsible for at least five deaths in the state and came two months after Hurricane Katrina devastated New Orleans' parishes.

The core of Irene will pass to the north of the Dominican Republic and Haiti Tuesday morning.