A week tomorrow, on Monday, etc. - Idioms by The Free Dictionary
a week tomorrow, on Monday, etc.
a week tomorrow/on Monday/Tuesday/etc.
One week from the day specified. Primarily heard in UK. I'm flying to Ireland a week on Saturday for my brother's wedding. We need that report finished a week tomorrow.
a ˌweek toˈmorrow, on ˈMonday, etc. (British English) (also a ˌweek from toˈmorrow, ˈMonday, etc. American English, British English ) seven days after the day that you mention: It’s my birthday a week on Tuesday.