The Washington PostDemocracy Dies in Darkness

D-Day at 70: The most important weather forecast in history

It’s a story describing how James Martin Stagg, technically not even a meteorologist, provided the final forecast which caused Supreme Commander Dwight D. Eisenhower’s Allied Expeditionary Force to decide to “embark on the great crusade” on June 6, 1944. Previously, the only weather forecasts Stagg had prepared were in Iraq, a very sore point with some of his colleagues. Stagg died in 1975.

One team of meteorologists, led by Irving P. Krick, one of the U.S. Army Air Force (USAAF) forecasters, relied heavily on analog forecasts from the past, but it was Stagg, the strong-willed Scotsman, whose forecast would be used and would carry the day. For many years afterward, however, Krick tried to take the credit.

Interwoven with all of the drama associated with Stagg’s forecast, the book includes a fascinating series of what-ifs. Ross speculates about some of the draconian results that might have ensued if there were a catastrophic failure of, or delay in, the invasion, code-named Operation Overlord.

I talked at length with Mr. Ross about his decision to write The Forecast and, after doing so, formulated some more detailed questions, which he was kind enough to answer. Following are some of these:

CWG: What prompted you to write this book?

Mr. Ross: I knew that Ike postponed D-day for 24 hours. After reading Isaac’s Storm, I wondered “Who was the D-Day weatherman?” [Isaac’s Storm was a best-selling book about the Galveston, TX meteorologist Isaac Cline, who was the meteorologist on duty when the catastrophic hurricane of September 1900 killed 6,000-10,000 Galveston residents in the deadliest weather disaster in U.S. history.]

CWG: What is your background?

Mr. Ross: Majored in journalism, minored in geography and geology, and worked summers for TVA [Tennessee Valley Authority] as a geologic aide, freelance outdoor writer since 1972, conservationist, reader of 20th century history–always more interested in the “why” of natural history than just the “what.”

CWG: With such a disparate background, what prompted you to write a book on the D-day weather forecast?

Mr. Ross: The D-day story is always told as a grand feat of personal courage and overwhelming material superiority, which it was. The only factor beyond control was the weather. It was a much bigger story than Isaac’s Storm, and nobody had written it.

CWG: How did you amass so much detailed weather information that was used in preparation for your book?

Mr. Ross: I’m a curious guy. Every interview and article raised new questions. And I was extremely fortunate to have very enthusiastic support from weathermen who actually helped make the forecast. They provided reams of documents and prompted me to explore every lead.

Mr. Ross: No, but I interviewed his wife and, later, one of his sons and daughter-in-law. They fleshed out his personality and presented a portrait of a man very different from what had been written about earlier. Stagg was born in Edinburgh in 1900 to a seamstress and plumber in a former stone stable. His mother insisted that his only path to social respectability was through education.

Ergo, he graduated from university, taught physics in private school, earned a masters degree, joined the UK Met Office, led the 1932 British Polar Year expedition to the Northwest Territories, was knighted, served 2-years forecasting weather for the RAF in Iraq, and after coordinating forecasting for the RAF and British Army was named the chief meteorologist for the Supreme Headquarters for the Allied Expeditionary Force (SHAEF).

CWG: After doing your research, did you find any aspects of the final forecast surprising?

Mr. Ross: Yes. 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.

CWG: Why did it take 10 years to write your book and what was the most difficult part?

Mr. Ross: I had to overcome a number of issues. Biggest was finding a publisher. I was (and am) too small a fish for my agent to devote a great deal of time advising me. Also, I was working on other publications: the 2nd edition of the Trout Unlimited Guide to America’s 100 Best Trout Streams (2004 Lyons Press); Rivers of Restoration (2008 Skyhorse), a book on Hospice that my late wife was doing when she died; and a 3rd edition of the trout guide.

CWG: Which government agencies helped you out?

Mr. Ross: Military History Institute at Carlisle Barracks, National Archives, National Climatic Data Center, British National Archives, UK Met Office Archives, UK Met Eireann Archives, and the U.S. Air Force and Coast Guard.

CWG: You say that President Kennedy asked Eisenhower why D-day was so successful and Ike said because of better meteorologists—but was that true, since wasn’t it more about the fact that the allies came in at low tide, which the Germans didn’t expect (not to mention the fact that the Germans expected the invasion at Calais)?

Mr. Ross: That statement is actually attributed to William Manchester from his biography of John F. Kennedy. Eisenhower may have said that we had better met[eorologist]s, but the truth is that although the Germans had excellent meteorologists, their forecasts between the Luftwaffe [ aerial warfare branch of the Germans], the Kriegsmarine (the Navy), and the Heer (the Army) were not coordinated well. The Luftwaffe  foresaw the coming of the front that blew ashore on the night of June 4/5, the date originally scheduled for D-day. On that basis, [German field marshal Erwin] Rommel  went to Germany [confident the rough weather would deter the Allies]. The Germans also picked up the break in the weather for June 6.

German strategy was actually flawed in three ways. First, as you say, they were convinced the Allies would land only at high tide to limit the long run across the beaches. However, the Allies came in at low tide to clear anti-landing craft obstacles. Second, also alluded to in your question, the German High command had assured themselves that the invasion would come only at Calais where the channel was narrowest. And finally, only Hitler himself could order reserve panzers [tanks] to repel the Allies on the beaches.

CWG: You say that there were skirmishes among Allied and German meteorologists in the Arctic. What connection did these have with the D-day forecasts?

Mr. Ross: Since weather over the North Atlantic moves from west to east, observations from the east coast of Greenland and Spitzbergen were critical to both sides. Therefore, each flew long-range weather reconnaissance missions and stationed weather ships in the North Atlantic. Without plane and ship observations from the Arctic, Allied and Axis meteorologists would have been all but blindsided by weather heading their way.

CWG: What about the secret agreement between the neutral Republic of Ireland to provide weather data to Great Britain? When was this agreement acknowledged?

Mr. Ross: Negotiations began in 1938 and were concluded in August, 1939, a few weeks before Hitler invaded Poland. The agreement was made public in 1953.

CWG: How important for D-Day were the clandestine western European weather observations made by Belgian, Dutch, and Polish meteorologists?

Mr. Ross: Probably not of extreme importance, but they were helpful if only to confirm intercepted German observations and forecasts. Polish meteorologists filled a very important role but not for the D-day forecast. Their observations were critical so pilots flying 1,000 miles to supply the Polish resistance could know the weather over drop zones.


Fortunately for the world, Project Overlord succeeded in breaching Hitler’s “Atlantic Wall” in little more than 4 hours, a structure that took several years to complete. The invasion was ultimately responsible for liberating western Europe and eradicating the scourge of Nazi Germany. As a result, Eisenhower never needed to issue a note he penciled on June 5, 1944, although the date actually (but mistakenly) said July 5

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.

Related reading: D-Day: The most important weather forecast in history (USA Today) | The toughest weather forecast of all-time, D-Day, June 6, 1944 (TheSIWeather) | The Weather Forecast That Saved D-Day ( | 70th anniversary of the D-Day landings and the role of the Met Office (UK Met Office)