NORMANDY — D-Day was originally scheduled for June 5, 1944, but was delayed by one day after Group Capt. James Stagg, a Scottish meteorologist, recommended postponing the invasion due to forecasted catastrophic weather conditions. The operation ultimately took place on June 6, 1944, with nearly 160,000 Allied troops deployed in the Normandy invasion.

Stagg presented his weather forecast to Gen. Dwight D. Eisenhower and other Allied leaders, advising that severe storms would endanger the amphibious assault if launched as planned. Though Stagg was not certain about the accuracy of his forecast, his recommendation carried enough weight for Eisenhower to make the decision to delay the operation.

Years later, when asked by John F. Kennedy what gave the Allies the edge on D-Day, Eisenhower responded, "We had better meteorologists than the Germans." The remark emphasized the role of weather forecasting in the invasion.

Stagg’s assessment contrasted with forecasts from German meteorologists, who predicted continued poor weather and did not anticipate an Allied landing on June 6. As a result, many German commanders were away from their posts, and defensive preparations were relaxed.