Weather forecasters say Tropical Storm Irene could become a hurricane by Monday, prompting the Dominican Republic to issue a hurricane warning.

The U.S.-based National Hurricane Center said early Sunday Irene is near the Leeward Islands heading toward Haiti, Cuba and possibly the U.S. state of Florida. The storm Sunday has winds of 85 kilometers per hour, and is expected to strengthen in the coming days.

Puerto Rico has put a hurricane watch in place for Irene – the ninth named storm of this year's Atlantic hurricane season.

Separately, Tropical Storm Harvey has been downgraded to a tropical depression after pounding Guatemala and eastern Mexico with heavy rain, prompting concerns over mudslides in the mountainous area.