HOLLYWOOD — The call sheet said 6 a.m. and the revised call sheet, issued at 9:40 the night before, said 6 p.m. Between those two pieces of paper, forty-one people rearranged a day, and eleven of them lost one.

Last week’s heat — four consecutive days above 100 degrees, peaking at 104 on Tuesday — did to Hollywood production what heat always does. Exterior units flipped to nights. Interiors moved up in the schedule where the schedule allowed. Two commercial shoots on rooftops cancelled and will reschedule in September. A backlot exterior for a streaming series went to a stage instead, at a cost the production would not discuss, and shot a scene written for daylight under a lighting setup built in six hours.

Working in the heat is not, on the whole, a matter of toughness. It is a matter of equipment and insurance. Above about 100 degrees, camera bodies and monitors begin throwing thermal warnings; makeup does not survive; a costume built for a period drama becomes a medical question. The industry’s heat protocols — mandatory shade, cooled rest breaks on a schedule, electrolyte provisions, a designated person whose job is to watch people rather than the shot — are decades old and reasonably well observed on a union set with a completion bond behind it.

“The safety part works,” said Lorna Petitjean, a costumer who has spent nineteen summers doing this and who was quoted in this paper last month weighing whether to leave the city. “I have never once been told to keep an actor in wool at 103. The part that doesn’t work is the money.”

Here is the arithmetic she means. A department head on a weekly rate is paid whether Tuesday happens or not. A crew member on a daily deal is paid for days worked. When a shoot flips to nights, most of the crew comes with it and picks up a night differential; when a shoot cancels, the people on weeklies are covered and the people on dailies are not. Local hires brought on for specific exterior days — additional grips and electricians for a big daylight setup, background performers, the drivers for picture vehicles that are now not being driven — simply do not work.

Of the forty-one people on that flipped call sheet, according to the production’s own count, thirty were on the show for the duration. Eleven had been hired for Tuesday. Nine of the eleven were absorbed into the night unit. Two were not.

“Two people is not a scandal,” the production’s unit manager said. “Two people is what happens. I would just rather the story said that two people is what happens, because at the end of a summer like this it is two people forty times.”

The larger cost of a heat week lands on the smallest operators, which in this neighborhood means the commercial and independent work that the summer permit figures have been celebrating. A five-day commercial with a two-day exterior has no margin to move; it either shoots hot, shoots at night at a premium, or eats the loss. Two producers said they had absorbed rebooking fees in the low five figures. One said she now writes a heat contingency into every summer bid and has been told twice this year that it made her uncompetitive.

Locations are the other pressure point, and it is a Hollywood-specific one. A rooftop is not a shade problem you can solve; there is nowhere to put a tent. Neither is the Boulevard sidewalk, where a crew works in whatever shade the buildings happen to throw at that hour and where, last Tuesday, a location manager measured 118 degrees on the terrazzo with an infrared thermometer and sent the whole unit into a restaurant’s back room for forty minutes.

The heat broke on Friday. The rescheduled rooftop spots go in September, the streaming series will make up its lost daylight with a second unit, and the industry’s summer will look, in the quarterly data, almost exactly as it would have.

The two people who were hired for Tuesday will not appear in that data at all.