The job: turn today's bookings into next week's plan
An occupancy forecast is not a prediction for its own sake. It decides how many staff are rostered, how much is bought for the kitchen, whether rates move, and whether the sales team spends this week chasing corporate accounts or not.
How it is done today
The most common method is last year plus a feeling. The manager pulls the same week from last year, adjusts for a known event, and writes a number. It is not unreasonable, but it ignores the single most informative thing available: how many rooms are on the books right now compared with the same point last year.
The second method is an arrivals report read as a forecast. That undercounts by definition, because it treats bookings not yet made as bookings that will not happen. Every property has a booking window, and forecasting without a pickup assumption guarantees a pessimistic number that nobody trusts.