Are food markets or grocery stores open on holidays in Paris?

Weekly markets are not scheduled on Mondays and Market streets are generally closed down on Mondays. Butcher shops and some other small specialty shops tend to be closed on Mondays. There will be bakeries and green grocers and grocery stores open. You won't have any trouble getting the basics but you will have to postpone a visit to a weekly market till Tuesday. I would not lay in cheese at a grocery store though -- wait until a cheese shop is open -- you might find one Monday but will certainly have many choices on Tuesday. Market streets will be open and all of the big market streets e.g. Rue Levis, Montorgueill, Mouffetard etc will have both butcher shops and cheese shops (and fish mongers and bakeries and specialty shops.

Yes, you will be able to find an open grocery store on Easter Monday. Not everything will be open, but something will be, enough for you to buy the necessities.

Some small neighborhood supermarkets should be open, such as: Carrefour City, Carrefour Express, Monop, Intermarché Express, U-Express, 8 a Huit .

Locate in advance on Google Maps those which will be close to your hotel and you will find everything you need to survive until the next morning.

when in doubt, look for a major train station

Thank you for the responses. Very helpful.