Lufthansa said a one-day strike by members of the ver.di trade union at several German airports would "stop flight operations".
At Munich specifically, Lufthansa grounded all of its flights on Sunday too (26 March). Operations at Frankfurt, Hamburg and Stuttgart are also set to be heavily impacted.
The union last week called on around 120,000 workers, including security personnel and ground handlers, to walk out.
Members of the ver.di union are being joined on strike by Germany’s rail union EVG, with German rail operator Deutsche Bahn warning services would be scaled back dramatically.
Other action will affect local transport services, such as buses and trams.
Germany’s airport association ADV pre-emptively warned the action could affect nearly 400,000 air passengers.
"Due to the extraordinary situation and the high number of cancellations, combined with only a reduced number of rebooking options, we will not be able to offer solutions for all passengers," said Lufthansa.
"We advise you not to travel to the airports without a confirmed booking for a flight. Unfortunately, it will not be possible to offer you any short-term rebooking solutions at the airport desks.
"Due to the regular passenger traffic on weekends, the airport halls are already heavily frequented."
