D-Day, June 6, 1944: The Most Important Weather Forecast In History

Today, we commemorate D-Day’s 70th anniversary, and looking back on the success of that day, we cannot help but think what might have happened had the weather forecast presented to Supreme Allied Commander Dwight D. Eisenhower been incorrect.

In those days, meteorologists didn’t have all the tools of 21st century technology, but those watching the weather conditions on Omaha Beach for June 5-6, 1944 had a great weight on their shoulders, for a mistake would have meant disaster for the Allied Forces.

The D-Day weather forecast was so important that when asked, years later, why the invasion went as planned, Eisenhower replied, “We had better meteorologists than the Germans.”

For the D-Day invasion to go as planned, the Allies needed to have low tide and perfect weather. The critical window of opportunity was between June 4 and June 6, but there was a strong, hurricane-like storm brewing.

As mentioned in an article on Myfoxdc.com, one of the meteorologists forecasting the weather for D-Day was Dr. Karl Johannessen. When he was interviewed for the 50th anniversary of D-Day, some 20 years ago, he remembered the fierce storm in the days before the invasion.

D-Day was originally scheduled to take place on June 5, 1944, but the weather forecast was not favorable, and Eisenhower moved it to June 6, which took the Germans completely by surprise.

In a new book titled The Forecast for D-day: And the Weatherman behind Ike’s Greatest Gamble, about Sir James Stagg, the lead meteorologist for D-Day, author John Ross tells the forgotten story of the most important weather forecast in history.

Just in time for the D-Day 70th anniversary, the publication of the book sheds light on the heated behind-the-scenes discussions among allied commanders about whether the largest land invasion ever attempted should be launched on June 5 or the next day, due to the unstable weather.

In a departure from protocol, Supreme Commander Eisenhower didn’t go with the forecast from the US Army Air Force (USAAF) but relied on that of Scottish meteorologist, Group Captain Sir James Martin Stagg, for his final decision on the D-Day invasion.

In an interview with the Washington Post, Ross points out all the things that could have gone wrong to make the D-Day invasion a disaster of historic proportions. Thanks to Stagg, and equal measures of good weather, great leadership, excellent planning, and heroic sacrifice (and a little help from Lady Luck), D-Day was a major success for the Allies, which led to the ultimate liberation of Europe and the end of Hitler’s reign of terror.

Ross also discussed his motivation for writing the book:

“The most surprising aspect of the forecast was that nobody had pulled together all the factors that went into making it – not the skirmishes between weathermen in the Arctic, not the role of weather in breaking the Enigma code, not the weather reconnaissance flights and weather ships, not the secret missions to measure the slope of the landing beaches to determine wave heights, not the clandestine weather reports from occupied Europe, not the opposing views of United States Strategic Air Forces in Europe (USSTAF) and British meteorologists, not the importance of readings from [neutral] Ireland, not the true picture of German forecasts, and not the unimaginable pressure felt not only by Stagg and his American deputy Col. D. N.Yates, but also by the men and women who took observations and plotted weather charts.”

“Equally surprising was that given the state of meteorology in the 1940s, Stagg got it right.”

One of the most astonishing little known facts about D-Day is that Eisenhower actually penned a note of defeat in case the invasion wasn’t successful, which read:

“Our landings in the Cherbourg-Havre area have failed to gain a satisfactory foothold and I have withdrawn the troops. My decision to attack at this time and place was based upon the best information available. The troops, the air and the Navy did all that bravery and devotion to duty could do. If any blame or fault attaches to the attempt, it is mine alone.”

Thanks, in part, to the precise weather forecast by Sir James Stagg and his team of meteorologists, D-Day was a success, and the Allies were able to land on the beaches of Normandy 70-years-ago today.