Whether we like it or not, weather is an important part in everybody’s daily lives. Most of us (if not all of us) get up and check it to see if the weather is going to cooperate with our plans for the day. Things were no different for one man in particular, General Dwight D. Eisenhower. Months of planning and training had already gone into Operation Overlord and it was on a tight schedule. There was only a small window where the full moon and subsequent high tide were favorable to launch the assault. With these primary considerations, the ideal date for the invasion was June 5, 1944..
I know, D-Day was June 6th not June 5th, but why the change? Well, if General Eisenhower had a WeatherWorks morning forecast that day it probably would have read something like this…
Monday June 5th: Overcast with periods of rain throughout the day. Extremely windy with gale force winds likely over the English Channel and along coastal France. (See Weather Map below)
Hardly weather for a combined amphibious and aerial assault. Unfortunately, delaying the invasion would mean waiting another 2 weeks for favorable moon and tides. Before taking such a large step backwards, Eisenhower consulted with Group Captain James Stagg of the Royal Air Force, Chief Meteorological Officer for Operation Overlord.
Captain Stagg had quite the forecast briefing to give (one that none of us here at the office would envy) to determine whether or not the most important operation of the war could proceed. Using input from three forecast teams (Royal Navy, Met Office, and US Army Air Force) as well as noted meteorologist Sverre Pettersen (Norwegian Air Force on loan to the Met Office) and Colonel Donald Yates (Eisenhower’s Staff Meteorologist) Captain Stagg concluded that there would be a brief improvement in the weather for June 6th (See Weather Map below) which would allow the invasion to proceed. Instead of pushing the invasion back to June 19th (which ultimately had even worse weather) the invasion was pushed back to the 6th.
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The low pressure system that had brought miserable weather on the 5th had moved off to the north and there was a brief break before the next system would arrive (See Surface Map above). Weather on June 6th was still not ideal; morning clouds prevented the aerial attacks that were meant to soften the German defense before the amphibious assault. This would ultimately lead to heavy fighting, and heavy losses, by the ground forces. However, German forecasters failed to forecast the brief improvement, resulting in many senior officers choosing this time for vacation and most of the lower commanders taking the time to participate in war games away from the coastal defenses.
With all wars, weather will invariably take some role in how everything plays out. The impact is usually negligible, however in this case significant gains/losses resulted. Good forecasting by the Allies allowed for the invasion to commence (though not entirely as planned); while poor forecasting by the Axis Powers left them without their senior leadership and caught them slightly off-guard for the attack. How would the remainder of the war have played out if the invasion occurred on June 19th (or later for that matter)? We can only speculate, but due to the hard work of the Allied forecasters the liberation of Europe was able to begin on this day.
