The Forecast for D-Day: And the Weatherman Behind Ike's Greatest Gamble

“An engrossing book that inspires the reader to consider a life of adventure, history, science, or, in the case of some of the characters in this story, combinations of all three.”

The story of how the Allied landings at D-Day were successful, partly due to accurate weather prediction, is a legend and even portrayed in motion pictures. As always in such history, the details are much more complicated and fascinating.

During the great global military conflict of the 1940s, the Earth was coincidentally at war with itself, presenting problems for all sides. Dangers even extended to droughts, forest fires, and volcanoes.

In The Forecast for D-Day, John R. Ross tells—in one highly representative slice of the weather war, how fog, rain, and wind affected aircraft and ships, not just soldiers slogging through the terrain. Before D-Day, the Allies had rough but educational experiences trying to transport troops in ships and land them in small boats in North Africa and Sicily.

The author explains that meteorology has a checkered history, particularly regarding military campaigns. “World War II’s generals and admirals were deeply schooled” in how “the very science of meteorology was suspect.” They “did not trust weather forecasts.”

Desperate commanders wanted timely weather information, often at the risk that it was dangerously wrong. Rossi writes that General Dwight Eisenhower needed a five-day forecast for D-Day when “1940s weather forecasting beyond the next day or two was hit or miss.”

The weather was an enemy to anyone planning “effective operations.” Defeats and victories took strange forms. The capture of a German weather ship gave the Allies crucial German decoding equipment. Had Eisenhower not accepted it, one forecast would have likely been a disaster for the invasion of France, as would have been the other days in June available for the landings.

Two clashing high-pressure systems in the North Atlantic meant that both sides had to use surface data from distant sources for timely weather prediction. This story mentions the Belgian and French resistance and Allied efforts to hide weather information from the enemy. The British intercepted and decoded German meteorological transmissions.

All the Germans needed to defeat the invasion was unpredictably bad weather. Delaying the Allied victory could have brought more German rockets against Britain and allowed the Soviet Union, which had its meteorological problems, to overrun more of Europe. Rossi argues that it might have affected the 1952 United States elections.

American meteorologists had the advantage of a country so vast that information telegraphed could be used to chart the movement of fronts over great distances. Northern Europe, the author explains, was much smaller and closer to the Arctic Circle, making timely predictions more difficult.

The Forecast for D-Day is an engrossing book that inspires a reader to consider a life of adventure, history, science, or, in the case of some of the characters in this story, combinations of all three. As the German U-boats waged war on Allied shipping, the Allied navies did so on enemy weather ships. The author includes the adventures in the battle for the Arctic for weather information.

Ultimately, the prediction for D-Day, the invasion of northern France, fell to James Martin Stagg, not a meteorologist but a Scottish-born geophysicist and explorer. Rossi writes that he proved a good choice from his ability to pull together the available information into comprehensible reports. Stagg was assisted by the often-contentious meteorologists Irving Parkhurst Krick and U. S. Military Academy graduate Donald Norton Yates. Krick’s predictions, although timely, were frequently wrong.

Stagg worried about his forecast to the last minute and sought minimum time and weather requirements from every planner to make the invasion work. He included fog and bombers, as well as the needs of the airborne troops. Factors such as the availability of landing craft and tides were as intractable as the weather. Sometimes, information was obtained by men who swam up on the enemy shores to report back on conditions and fortifications.

Much of the story of Eisenhower’s decision to trust Stagg's prediction is about the management and work of many individuals and the discoveries at the beginning of the modern age of meteorology. These often-continuous meteorologists used three forecasting systems from “competing American universities and were bitter rivals.”

The Forecast for D-Day is well-written, easy reading prose that avoids boring the reader with too much scientific technical explanation. Telling this story is guaranteed to have organizational issues. This work has annotations, a glossary, illustrations, and maps.