Insights & News

D-Day 75th Anniversary: A Historic Weather Forecast

31st May 2019

During 2nd-9th June 2019, spanning the anniversaries of the battle of Normandy and D-Day (6th June), the Daks over Normandy events will launch a summer of celebration and remembrance.

We find out how weather risk prediction played an essential role in making history…

The D-Day 1944 Weather Forecast

75 years ago, one of the most important weather forecasts in history was put together, to guide military planners on the best date to carry out the legendary invasion.

At the time, meteorologists (weather forecasters) and other specialists studied weather patterns and tides. These individuals initially advised that the D-day date should fall between 5th and 7th June. Preliminarily, the earliest of these dates was chosen.

However, following concerning predictions of deteriorating weather conditions, Supreme Commander General Dwight D Eisenhower made the difficult decision to postpone the invasion to the 6th June. Strong winds and rough seas would have posed an unjustifiable destructive risk to the Mulberry harbours and the landing craft critical to the invasion.

With every hour’s delay came an increasing risk that details of the operation would fall into the hands of opposing forces.

Eisenhower’s chief meteorologist, Group Captain James Stagg, predicted a temporary break in the weather on 6th June. On this information, Eisenhower ordered that the invasion proceed.


The D-Day 75th Anniversary 2019 Weather Forecast

75 years on, as commemorates gather in a politically uncertain European climate, will there be stormy weather to contend with, or are we looking more fortunate?

Clearly, forecasting techniques have come a long way since 1944, as MetSwift’s ground-breaking work in weather risk prediction evidences. Confidence in weather prediction continues to grow as the intelligence available to us evolves. This is a fascinating achievement in the face of the weather’s inherently chaotic nature. As climate becomes increasingly politicised, it’s certainly strange to contemplate this transition in terms of historical events, intergenerational memories and future progress.

‘This is a fascinating achievement in the face of the weather’s inherently chaotic nature.’

As of writing this (31st May), our guidance tools suggest that unsettled weather with showers or longer spells of rain is very likely (a 9 in 10 chance!). That’s an unusually high probability for such weather in early June. However, they also suggest only a 1 in 10 chance of it being windy enough to bring rough seas.

Had these guidance tools existed a week before D-Day in 1944, they might well have painted a similar picture. It seems as if meteorological history is repeating itself.

Based on past experience and the expected behaviour of major driving forces behind our weather patterns, I believe that the chance of a drier, calmer day is at least a little higher than the guidance tools suggest. Even so, it’s not looking great I’m afraid. For those gathering in remembrance in the UK and France, weather events during the commemorative week may prove evocative.


My own grandfather will be a part of the celebration and memorial events this month, as one of the 300 World War II veterans who will board the specially chartered MV Boudicca in Portsmouth and figuratively recreate the famous crossings to Normandy of 75 years ago.

As long as I can remember, he has inspired me to aim high and keep my goals in my sights, no matter how tough the going gets. I know I can never truly give as much as veterans such as him have, but I intend to reach as close as I can.


James Peacock MSc

Head Meteorologist at MetSwift

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