Timeshare weeks are numbered, not dated, and the numbering is not the ISO week
number people usually reach for. On Interval's calendar week 1 starts on the
first Friday of the year, and the Saturday and Sunday following that Friday
belong to the same week. Pick a year to see exactly which dates each week
covers, and overlay a market's Travel Demand Index to see what those weeks are
worth.
—
Week
Friday check-in
Saturday
Sunday
Friday stay
Demand
TDI
How the numbering works
Interval ties Friday, Saturday and Sunday together: all three check-in days in
the same seven-day span carry one week number, anchored to the first Friday of
January. RCI numbers those days independently, which is why the same physical
week can carry different numbers in the two systems.
A year has 53 numbered weeks only when a 53rd Friday still falls inside it —
2027 does, because its week 1 starts on Friday 1 January. In a 52-week year the
demand charts still publish a row 53, and that is not an error: those check-in
dates exist, they simply fall in January of the following year. Week 53 of 2026
is Friday 1 January 2027.