Metro riders are permitted to carry and consume water throughout the system Thursday afternoon through Monday night, the Washington Metropolitan Transit Authority announced.

WMATA is allowing water — and only water — because of the expected extreme temperatures over the weekend. Much of the region will be under an excessive heat watch Friday. The National Weather Service forecasts a high of 99 degrees in Arlington on Sunday.

The lift on Metro’s no-drinking policy will remain in effect until the system closes Monday night. Water can be consumed on trains and busses and in stations.

WMATA encourages riders to use water containers that can be tightly secured and to use trash receptacles to dispose of any waste.

Riders are cautioned that the expected high temperatures can place a strain on Metro and that unplanned delays and service interruption are possible. 

Metro track work remains scheduled this weekend for the Orange, Blue and Red lines.