Schools and universities in the two US territories will be closed today as the storm approaches.
Forecasters say on the current trajectory it will make a direct hit on northern Guam and CNMI's Rota island.
The CNMI Governor Ralph Torres has raised the alert for the typhoon to condition 2.
Typhoon Mangkhut is forecast to bring destructive winds of 74 miles per hour or more possible within the next 24 hours.
Mr Torres has activated essential government agencies like the police, hospital, airports, and seaports.