This Monday is the Easter monday, which in some Spanish communities is celebrated as a public holiday. Specifically, this year there are six in which this Monday is not working: Balearic Islands, Catalonia, Valencian Community, Foral Community of Navarra, Basque Country and La Rioja.
Therefore, the opening and closing hours of the main supermarket chains may be affected this Monday.
Mercadona supermarkets have a regular schedule that runs from 9:00 am to 9:30 pm, but it is the policy of the Valencian company not to open on holidays.
Thus, the Mercadona of the communities where this Monday is a holiday they won’t open, but yes where this Monday is working. In this link you can consult the information about the schedules.
The French chain of hypermarkets Carrefour does not have a uniform policy of opening days, since depending on where it is located open or not on holidays.
When it opens, it does so on a regular schedule of 08:30 a.m. to 10:00 p.m., although sometimes, when it opens on holidays, a reduced schedule applies, from 10:00 a.m. to 9:30 p.m. In this link you can check whether or not it opens in your community.
Lidl supermarkets usually have a business hours 09:00 to 22:00 hours from Monday to Saturday, although if they open on holidays they usually do it an hour later.
However, in some autonomous communities they do close Sundays and holidays. In this link you can check if your Lidl store opens or not in your community.
The DIA and La Plaza supermarkets have regular opening hours 08:30 to 22:00 hours, although in some of the autonomous communities they can opt for reduced hours, closing at 2:00 p.m.
In this way, check all schedules of the DIA stores in the different cities in this link.
The usual hours of the hypermarkets of the Alcampo firm are 9:00 to 21:30 hours from Monday to Saturday, although it can also open on holidays.
In this link you can check the schedule of each of its stores for this Easter Monday.