Weather Risk Calendar

What the number actually depends on

Hamburg averages 17 rain days in December — a 3-day exterior shoot then has a 55 % chance of losing at least 1 of them.

Rain probability and rain volume are 2 different numbers: 2 mm of drizzle stops a beauty shot but not a documentary.

The gap between a number that goes into a quote and one that holds on the day is rarely the formula — it is whether the constraints were entered honestly. That is why the inputs are spelled out below.

Common mistakes

The places where the arithmetic is right and the day still falls over:

• Booking exteriors on consecutive days with no cover set
• Reading a monthly average as a daily forecast

In day-to-day production

A cover set costs 1 location fee and saves an entire day — the cheapest insurance in the schedule at roughly 3 % of a shoot day.

The number belongs in production planning — the point where a decision is still free to change. Working it out on the shoot day is no longer calculating; it is finding out.

In TillyGen this is not a separate step: the result sits inside the plan itself, alongside the shot list, schedule and call sheet. Change a constraint and the dependent values move with it — the affected parts of the plan are flagged rather than quietly left behind.