The Rail, Maritime and Transport (RMT) union will go on strike for 24 hours as part of the long-running dispute with Northern Rail, the franchise now run by Arriva.
Members will strike every Saturday until the end of the month, the union confirmed this week.
Why are they striking?
The dispute is borne out of the union's fight to keep what it describes as "a safety-critical guard" on Northern trains.
However, Northern has continued to stand firm throughout the two-year row over plans to implement "driver-controlled operation" services, which it insists are safe and in "regular use" across rail networks in the UK and overseas.
The company said it has also committed to having a second ember of staff on-board, in addition to the driver.
What services will run?
Northern has confirmed it will continue to run about 700 services tomorrow.
However, it has said that "very few" will be in place after 5pm.
"Those Northern services that do run, and other operators’ services, are expected to be extremely busy," a statement on its website said.
Trains will be 'extremely busy'
The company has urged people to check timetables and its website to plan ahead.
David Brown, managing director at Northern, said: "We expect all of our service on Saturdays in January to be extremely busy and are calling on our customers to plan their travel carefully for the coming weekend, check the new timetables well in advance, and make sure they do not rely on the last trains home.”
What stations will be affected?
Stations in the region to be affected by the industrial action include Middlesbrough, Scarbrough, Hull, York, Harrogate, Leeds, Wakefield, Bradford and Huddersfield.