New film revisits how forecasters shaped the fate of D-day
A new film, Pressure, dramatises how Second World War meteorologists, working with scarce data, predicted the weather window that allowed the D-day landings to proceed on 6 June 1944. Historians and meteorologists describe how difficult that call really was.
A new film titled Pressure, based on true events, is showing in cinemas across the UK and Ireland from 9 September. It tells the story of the meteorologists behind the 1944 D-day landings in Normandy, centring on Captain James Stagg, who had to advise Gen Eisenhower on whether weather conditions would allow the invasion, originally planned for 5 June, to go ahead.
Forecasting without modern tools
Dr Stephen Burt of the University of Reading, who advised on the film, explains that forecasting more than 24 hours ahead in the 1940s was an enormous challenge. Meteorologists at the time had only a handful of ship, submarine and aircraft observations to work with, lacking satellites or the transatlantic data available today. The week before the planned landings had brought the hottest May on record, a record only broken this year, followed by a major storm with another close behind.
Prof Ed Hawkins of the University of Reading notes that three separate teams produced forecasts, each reaching different conclusions, leaving Stagg to reconcile their findings into a single recommendation that would affect 160,000 Allied troops. The teams initially disagreed on the outlook for 5 June, and Stagg judged conditions too dangerous, so the landings were postponed. By the evening of 4 June, however, a consensus formed that a brief, workable window would open on 6 June, and the invasion went ahead.
Faithful historical detail
Met Office archivist Catherine Ross says the filmmakers were given exact replicas of the weather charts, codes and documentation used in June 1944. She notes that Allied forecasters already had an advantage through access to UK and Atlantic data, and that codebreaking at Bletchley Park had also given them German weather observations. German forces, while aware of the storms, missed the brief improvement in conditions that the Allies spotted.
Experts say that even modern AI-based forecasting systems, using the data available at the time, would struggle to accurately predict the conditions of 6 June 1944. Ross calls it one of the most significant weather forecasts in history.
