This is the ld + json format, but say you are closed for Christmas, just leave the open and closed hours empty, as I did for the usual openingHours below. This test business is closed on Sunday, so I just do not enter at this time.
... "telephone": "123-555-1212", "openingHours": "Mo,Tu,We,Th 09:00-19:00, Fr 09:00-20:00, Sa 09:00-18:00", { "@type": "OpeningHoursSpecification", "validFrom": "2015-12-25", "validThrough": "2015-12-25" }, "address": { ... }
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