A Narrow Weather Judgment Helped Decide When D-Day Could Happen

Meteorology was not background scenery to the invasion; it was one of the conditions that made it thinkable.

The invasion decision was intertwined with weather analysis. Allied meteorologists judged there would be a brief improvement in conditions sufficient for the landings, while German assumptions did not fully anticipate the chosen window. The obscure pleasure is that vast human movements sometimes hinge on the confidence of experts reading patterns in wind and pressure. It is one of the most dramatic examples of a forecast entering history as an operational actor.