Travellers had been hoping for some return to normality after cabin crew called for two bouts of industrial action earlier this month.
Ryanair had assured that there would be no disruption to its Irish flights in July “as a result of such poorly supported Spanish labour strikes”.
But now two Ryanair cabin crew unions, Unión Sindical Obrera (USO) and Sitcpla, have called for a walk out that will last five months from August 8
The industrial action will take place every week, from Monday to Thursday, and will last 24 hours, it has been reported by Euronews.
According to USO sources quoted by Euronews, demands include a call for the immediate reinstatement of 11 workers fired for striking this July.
"We are seeing a trickle of dismissals almost daily. Last week it was the tenth worker and yesterday another colleague from Barcelona who had been with the company for 12 years," union sources have been quoted as saying.
They are also calling for an end to disciplinary proceedings against almost 100 workers who took part in the stoppages.
"They are using this as a way of intimidating the workforce. It is their way of warning workers to be careful about going on strike," a union spokeswoman added
"There has not yet been any kind of cooperation on their part," the USO claimed.
The 18 days of strikes since the beginning of the summer caused an estimated 310 cancellations and about 3,455 delays at 10 Ryanair bases in Spain.
This new action will mainly affect the airports of Madrid-Barajas, Barcelona, Malaga, Alicante, Seville and Palma de Mallorca. Both national and international connections will be disrupted.
The general secretary of the USO unions at Ryanair, Lidia Arasanz has said they were “forced” to stage new days of strike action due to the company “not listening” to its workers.
“It is not worth sitting down at the negotiating table again,” Ms Arasanz added. “We are talking about the fact that we have 11 workers fire and more than 100 on file for exercising fundamental rights.
“We have already said that we are not going to leave any worker behind.”
The workers' demands include "the application of basic labour rights", that include 22 days of annual leave for cabin crew as well as 14 public holidays and the reinstatement of salary rates that were being paid pre-pandemic.
According to a statement issued by Ryanair it expects minimal, if any disruption, in Spain this winter.
It adds that Ryanair has reached an agreement with the main Spanish union CCOO on wages, rosters, and allowances for cabin crew.
“Recent USO/SITCPLA strike have had little support and minimal effect,” the statement reads, according to local media.
“Ryanair has operated over 45,000 flights to/from Spain in the last three months with less that 1% of crew affected and expects minimal (if any) disruption to operations scheduled for this winter.”