Image courtesy of the Sweeney family
Image Caption, Maureen Sweeney’s weather forecast influenced Eisenhower’s decision to postpone the Normandy landings Article Information Author, Geoff Maskell Role, BBC News NI 4 June 2024
Updated 2 hours ago
As a young woman growing up in County Kerry, Maureen Flavin Sweeney dreamed of emigrate to America.
Belmullet, in County Mayo, on Ireland’s Atlantic coast, was the westernmost point she reached.
There she married a lighthouse keeper, raised a family, and made the weather forecast that changed the course of history on June 4, 1944.
Built in 1866, Blacksod Lighthouse offers no less spectacular views across the vast ocean.
However, it has a geographical advantage as it is located in the westernmost part of Europe.
For planners of the Normandy landings in southern England, Sweeney’s forecast would be their first indication of changing weather conditions.
After a month of stability in May 1944, the situation by early June became much more unfavourable for those planning a re-entry operation into Nazi-occupied France.
What is D-Day?
The operation, D-Day, or the Normandy landings, saw British, American, Canadian and French forces attack German forces on the coast of northern France on 6 June 1944.
It was the largest naval invasion in history and one of the most crucial events of World War II, marking a turning point in the fight against Nazi Germany.
But Operation Overlord required very specific conditions: it had to be carried out just before dawn, at high tide, and ideally on a night with a full moon.
This limited the available dates to May 21-23, June 5-7, June 18-20, and July 3-5, 1944.
Between Opportunities
Image courtesy of the Sweeney family
Image caption: Blacksod Lighthouse, photographed in the 1940s
The May dates were postponed for logistical reasons, and on the night of June 2-3, Sweeney reported bad weather, a sudden drop in pressure, and winds of Force 6.
This report was forwarded by the Irish Met Office to Allied headquarters in the south of England.
Unusually, Sweeney received a call back a short time later.
It was a woman with a British accent who had come to ask for confirmation of the report.
Her future husband, lighthouse keeper Ted Sweeney, had just returned home when the phone call came.
“I checked it multiple times and the numbers were the same both times so I was happy,” she later told the Irish Eye.
It was a call that shaped history.
Image caption: Colonel James Stagg’s predictions led Eisenhower to postpone the operation
The most important predictions in history
Ultimately, D-Day, June 6, involved approximately 12,000 aircraft, thousands of ships, and 150,000 soldiers.
Weather reports from Belmullet were sufficient for the Chief Meteorological Officer, Colonel James Stagg, to recommend a postponement of the invasion for 24 hours.
“The situation from the British Isles to Newfoundland has changed dramatically in the last few days and is now potentially threatening,” Stagg told General Dwight D. Eisenhower.
For Allied soldiers waiting under their tents in camps across southern England, the weekend of June 3-5 was marked by strong winds, low cloud and rough seas.
On Saturday, June 3, Eisenhower issued a postponement order.
Image courtesy of the Sweeney family
Image Caption: Ted and Maureen Sweeney were married in 1946
Weather improvement
Eisenhower and his commanders faced a real dilemma: balancing secrecy with success.
Launching an invasion in bad weather risks failure, and delays increase the chances of the invasion plans being leaked.
British Prime Minister Winston Churchill had already banned travel and communication between the north and south of Britain and Ireland on 14 March 1944.
However, under an agreement concluded between the two governments in May 1939, weather information was still received from neutral Ireland.
Information was provided hourly from 10 weather stations across Ireland, including Blacksod, with key information coming in on 4 June.
Captain Stagg believed that a ridge of high pressure was forming off the Azores.
A ridge with a high chance of good weather.
Confirmation was received on 4 June when Ted Sweeney reported from Belmullet that “the heavy rain and drizzle had ceased, the clouds were at a height of 900 feet and visibility over land and sea was very good”.
At 4:15 a.m. on June 5, 1944, Eisenhower met with his senior staff and told them, “OK, we’re going.”
Image courtesy of the Sweeney family
Image caption: Maureen Sweeney receives a medal from the U.S. House of Representatives
Maureen and Ted married after the war, but neither of them knew about the role they had played on D-Day until 1956.
That year the weather station was automated and moved from the lighthouse to the town of Belmullet, and its secrets were passed on to the couple.
This was made more public in 2004 with the unveiling of a memorial at the lighthouse, and in 2020 Maureen Flavin Sweeney, then 98 years old, received a special honor from the U.S. House of Representatives for her wartime service.
The importance of weather
If the invasion had been postponed again until the next possible date, 18 June 1944, the outcome might have been very different.
That week, the worst storm in 40 years reached the English Channel, making landfall impossible.
In 1961, on his way to the inauguration, President John F. Kennedy asked Eisenhower why he had the advantage in the Normandy landings.
He replied: “Because we had better meteorologists than the Germans.”
Meteorologists tasked Maureen and Ted Sweeney with keeping a close eye on the weather in the countryside on Ireland’s west coast.
