Thick cloud hung over France and the Channel on the morning of D-Day as one of the largest and most dangerous seaborne invasions in history got underway, new images reveal.
Scientists have turned weather records from 1944 into a recreation of what the world might have looked like from space as 160,000 troops stormed the beaches of Normandy.
It shows cloud stretching across Britain and much of the Channel with patches of southern England and northern France starting to peek through, indicating the sky was clearing.
And just in time – as the mission could have failed if the storm had not eased off.
The weather was crucial to the success of D-Day because the Allied invasion force relied on a rare combination of conditions, including low tide, moonlight and relatively calm seas.
Professor Ed Hawkins, climate scientist at the University of Reading, co-created the images with scientists from the European Centre for Medium-Range Weather Forecasts (ECMWF).
‘Troops set off into a sky that was still breaking up after days of storms into a narrow window of better weather,’ he said.
‘A day earlier, or a few hours either way, and the weather could have stopped the invasion in its tracks and changed the outcome of the war.’
In the early hours of June 6 1944, thick cloud covered southern France and the Channel (left). Pictured: A recreation of cloud cover at midnight
However, there was a small break in the clouds later that morning, allowing the Allied forces to mount a successful invasion. Pictured: The clouds clearing six hours later
On the advice of military planners and meteorologists, D-Day was initially set for June 5.
More than 5,000 ships carrying troops, tanks and supplies were assembled in southern England, ready to launch the largest amphibious invasion in history.
In the days leading up to it, Allied commanders anxiously monitored weather forecasts as powerful storms battered the English Channel.
The stormy weather forced General Dwight D. Eisenhower to postpone the landings by 24 hours.
But a brief break in the conditions on June 6 gave troops their chance to cross the English Channel and reach the beaches of Normandy.
The Germans, believing bad weather made an invasion unlikely, were caught off guard when Allied soldiers landed as part of the enormous seaborne assault.
The new satellite images were built using old weather readings fed into a modern weather reconstruction.
This filled in the gaps between real measurements to recreate a full picture of the sky.
This global satellite recreation shows just how far the cloud cover reached – revealing just how narrow the margin was between success and failure
A U.S. Army landing craft approaches Omaha Beach on June 6, 1944, where the heaviest fighting took place and thousands were gunned down on both sides
‘Images like this help us understand what troops, sailors and pilots actually faced that day, in a way written reports alone cannot,’ Professor Hawkins said.
‘They show just how narrow the margin was between success and failure, and how much was riding on a small break in the cloud.’
The remarkable true story behind the weather forecast that helped shape history is the focus of an upcoming film called Pressure.
The film, which explores the pivotal decision to delay the Allied invasion, stars Andrew Scott as Group Captain James Stagg, the meteorologist who advised Supreme Allied Commander General Dwight D. Eisenhower, and Brendan Fraser as Eisenhower.
The synopsis reads: ‘In the 72 hours leading up to D-Day, all the pieces are in place except for one key element – the British weather.
‘Britain’s chief meteorological officer James Stagg (Andrew Scott) is called upon to deliver the most consequential forecast in history, locking him into a tense standoff with the entire Allied leadership.
‘The wrong conditions could devastate the largest ever seaborne invasion, while any delay risks German intelligence catching on.
‘With only his trusted aide Captain Kay Summersby (Kerry Condon) to confide in, and haunted by a catastrophic D-Day rehearsal, the final decision rests with Supreme Allied Commander Dwight D. Eisenhower (Fraser). With only hours to go, the fate of the war and the lives of millions hang in the balance.’
The remarkable true story behind the weather forecast that helped shape history is the focus of an upcoming film called Pressure (pictured)
In the weeks before D-Day, Allied forces carried out a major rehearsal known as Exercise Tiger off the coast of Devon.
Disaster struck when German E-boats attacked a convoy of American landing ships in Lyme Bay, killing 749 US soldiers and sailors.
The tragedy was kept secret to avoid alerting the Germans to the invasion plans.
But it exposed serious communication and co-ordination problems that commanders worked to fix before the Normandy landings.
