D-day and the most important weather forecast in history (2024)

Published

6 June 2024

As a weather presenter and former RAF reservist, I'm taking a look back at one of the most crucial weather forecasts in history and how forecasting expertise remains fundamental to the military 80 years on.

With stormy conditions in the English Channel D-Day, planned for 5 June 1944 was under threat.

But a team of meteorologists led by Group Captain James Stagg noticed a window of quieter weather and it was launched 24 hours later.

This demonstrated the importance of weather forecasting in military planning and operations.

Even today a group of specialist weather forecasters make crucial decisions to help the armed forces.

The weather forecast was key. With a full moon and favourable tides in early June, D-Day - the launch of boats in an amphibious attack on the beaches of France, known as Operation Overlord - needed good weather.

In the final days of planning Allied commanders looked to the meteorologists for their advice on weather conditions.

But it wasn't looking good and the lives of tens of thousands of soldiers were in jeopardy.

In 1944 weather observations were sent by coded message and used to produce hand-drawn weather charts.

Using this limited information, meteorologists made a forecast that was only really reliable for 24 hours ahead.

Stormy weather in the Channel threatened D-Day but Group Captain Stagg noticed a quieter window of weather developing.

After a 24 hour delay, this forecast was written into history with the successful launch of Operation Overlord on 6 June 1944.

Group Captain Stagg was one of the first meteorologist to openly discuss the use of weather forecasts to gain military advantage.

He spoke of "picking out [a weather] interlude that would be unknown to the enemy forces that would allow us [Allies] to make use of it and catch the people on the other side unawares".

Eighty years on Stagg's thoughts remain just as important.

Since D-Day, weather forecasters have continued to support the Armed forces.

While the Navy has its own meteorological branch, the Royal Air Force and Army are supported by a specialist group of meteorologists from the Met Office who are also sponsored RAF reservists - called the Mobile Met Unit (MMU).

The MMU is deployed around the world, providing meteorological information to ensure safe and effective military operations.

As a former member of the MMU, I have been on operations in Iraq and Afghanistan, and have first-hand experience of how crucial the weather forecast can be.

On one occasion at Camp Bastion, in Afghanistan, I put out a forecast for high level cloud to move into an area.

Due to meteorological conditions and aircraft limitations, it meant that a certain level of cover - known as overwatch - was limited for British troops.

This had a direct impact on a platoon who were doing some patrols in the Helmand province - and I received a phone call from the troop commander, asking me to change the forecast.

Of course I couldn't do that, but at the time it really struck me how a decision made by a weather forecaster could directly impact a soldier on the ground.

Technological advances with super computers, satellites and meteorological data mean that we are able to forecast the weather in more detail and much further ahead than was possible 80 years ago.

However, the weather can still bring challenges.

Aircraft have limits in the weather they can safely operate, so need detailed forecast information.

For commanders, the weather forecast will often be the deciding factor for a "go" or "no-go" operation.

Gaining an advantage over the enemy is also considered, just as it was in 1944.

As Flying Officer Rosie Hill, MMU forecaster explained: "If we understand the weather better, then we can use that to our advantage, maybe forward plan better and make operations more efficient."

The MMU has recently supported a number of Nato exercises in Eastern Europe to deter Russia.

Around 16,000 British Army personnel were deployed on Exercise Steadfast Defender, making it the largest of its kind in the last four decades.

Forecasters were integrated into an Army aviation brigade that was commanding troops from 17 nations across eight countries with numerous helicopters from the United Kingdom.

The MMU played a critical role within the UK aviation element.

MMU Ops Officer Flight Lieutenant Derek Percival explained:

"Our teams are living and working in the field as an integral and vital part of the decision making process in a major Army HQ.

"In Nato's largest exercise in years, a major parachute drop and beach landings had to be delayed due to bad weather but our forecasters were able to advise commanders of a small window of better weather 24 hours later.

"It had all the similarities of the D-Day forecast."

Eighty years on, although weather technology has changed and forecasts are more accurate, the potential impacts of the weather remain the same.

Military commanders will continue to need the expertise of weather forecasters to make safe and effective decisions.

And, to use the weather forecast in gaining the military advantage.