From the MBTA website:

Weekend Service Returns to All Commuter Rail Lines July 3

Posted on June 14, 2021

Expanded service hours to provide a new weekend transit option for shift workers.


The MBTA and Keolis Commuter Services (Keolis), the agency’s operating partner for Commuter Rail, are reminding passengers that weekend service will resume on all Commuter Rail lines effective Saturday, July 3. Schedules are now available to view on mbta.com/commuterrail.

 
Rail service on Saturdays and Sundays will return to the Fitchburg, Franklin, Greenbush, Haverhill, Kingston, Lowell, and Needham lines. Saturday and Sunday service will be identical across all lines.   

 
“The resumption of weekend service represents a major milestone in the MBTA’s aggressive plans to restore service to meet rider demand,” said MBTA General Manager Steve Poftak. “With the public’s health and safety of paramount importance, we remind our customers that face coverings are still required while using all MBTA services. As we navigate the ‘new normal,’ we are designing our service schedules to best serve riders who have used the system throughout the pandemic as well as returning and new customers.”