Workers at train company Northern have begun a 24-hour strike in a long-running row over driver-only operated trains.
Members of the RMT union plan to walk out on six consecutive Saturdays until 29 September.
People attending major events on Saturday, including Manchester Pride, Creamfields and Leeds Festival, are told to be aware of a reduced service.
Northern said it would operate about 30% of its usual services.
Very few of its trains will run before 09:00 BST and after 18:00, a spokesperson warned.
The rail union has accused Northern of “refusing point blank to engage in serious and meaningful talks”.
The union claimed driver-only operation was being extended “in the name of increased profits”.
Northern deny a lack of communication, and in response said: “We maintain that talking costs nothing, whilst strike action causes inconvenience to customers and damages the case for long-term investment in rail.”
Large events impacted by the Saturday rail strike
- Manchester Pride
- Leeds Festival
- The Great British Rhythm and Blues Festival in Colne
- Bolton Food & Drink Festival
- Redcar Races
- Cartmel Races
- York Ebor Festival
Attendees planning to travel by rail are advised to check what services are available before they leave
Northern services cover the North West, North East, Yorkshire and the Midlands.
The RMT has instructed members not to book on for duty between 00:01 and 23:59 on 25 August and every Saturday in September.
Mick Cash, RMT general secretary, said: “Members have been in dispute for well over a year now in a battle to put public safety before private profit and we are angry and frustrated that a genuine opportunity to reach an agreement has been kicked back by the company.
“Northern Rail want to run nearly half a million trains a year without a safety critical guard on board in a move that would wreck both safety and access to services.”
A Northern spokesperson said: “This weekend, there are a large number of important public events being planned right across our region, on what will be the last holiday weekend of the summer.
“People going to these events rely heavily on our services – RMT’s strikes will cause unnecessary travel disruption and delays for what should be weekends of fun, enjoyment and celebrations.”