From what I understand, the June 1944 landing at Normandy was kind of an "iffy" thing, because of the weather. That's because there were only a few windows of opportunity each year, when the tides were properly aligned, and then only if the "atmosphere" cooperated. If the invasion hadn't taken place on June 6, there was only one more theoretical opportunity in July, 1944, one that wouldn't have materialized, because of the "air." Without the June 6th invasion, the invasion would have to have been postponed until 1945.

Did the Germans face similar tide and weather issues with their "Sea Lion" plans for the invasion of England? On one hand, they had a wider choice of landing sites than the western end of the English Channel, but on the other hand, their landing craft was far less sturdy. Was it a situation where the Germans would not only have had to win the (air) "Battle of Britain," but have control of British skies on a few critical days that mattered because most others did not?

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    I think that the weather would come a poor third behind beating the Royal Air Force and the Royal Navy. Just a hostile destroyer or two in among the landing craft could have caused havok.
    – Steve Bird
    Mar 6, 2017 at 6:16
  • @SteveBird: I was surprised to find that with 'total" air and naval superiority, the Allies were so particular about the weather. But the answer shows that apparently the Germans weren't.
    – Tom Au
    Mar 6, 2017 at 19:37
  • The Germans had no proper landing craft so the sea-state would have been critical, anything more than a mild swell would have sunk a lot of their craft en-route.
    – davidjwest
    Mar 15, 2017 at 11:40
  • @davidjwest: I suspected as much, but "suspected" is not the same as knowing. Why don't you put your comment in the form of an answer.
    – Tom Au
    Mar 15, 2017 at 12:30
  • One should note that the English had mined the hell out of the channel. Uboats were also useless due to its shallowness.
    – Hefewe1zen
    May 23, 2017 at 15:02

2 Answers 2


The Allies were fussy about the schedule for Normandy for a combination of reasons. They wanted a full moon to make night parachute drops easier, and a landing shortly after dawn with the tide half-way in. That would minimise spotting of the arriving fleet, and make the obstacles on the beach easier to see and avoid.

The tide and time-of-day conditions coincided twice a (lunar) month, one instance of which would also have a full moon. The next opportunity was 18-20 June, without the full moon, then there would have been one at the beginning of July with the full moon. But there would have been no question of putting it off until 1945. They'd have accepted less than optimal conditions first.

Operation Sealion wasn't planned in nearly so much detail, so these issues may not have emerged. The German paratroopers don't seem to have been set up for night drops, which would be rather dangerous given the unconventional single-riser parachute they used. There also weren't nearly so many obstacles on the beaches of southern England in summer 1940 as there were in France in 1944. However, the German landing craft would be much more vulnerable to bad weather and high seas. Sealion would have been dependent on good weather, the defeat of the RAF, and after that would still require Alien Space Bats to get rid of the Royal Navy.

  • Wouldn't the defeat of the RAF mean that the Luftwaffe could then concentrate on finding and destroying all RN units within range. Thus after the British detected the German landing craft coming the nearest surviving RN ships should have had to come from hundreds of miles away and been under Luftwaffe attack after being detected by the Germans. And before the real invasion the Germans could have sent decoy invasion forces with dummies in the landing craft and when the Royal Navy ships were close enough bombed them from the air while the landing craft turned back.
    – MAGolding
    Mar 6, 2017 at 19:15
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    @MAGolding: That would work, if the Luftwaffe was as good at finding and sinking ships as it claimed. The Royal Navy had found in the Norwegian Campaign that the Luftwaffe could be held off, until you ran out of AA ammunition. Defending the UK, with plenty of ammo available, the RN would have given the Luftwaffe a very hard time. Mar 6, 2017 at 19:22
  • @MAGolding, you have a point. I find it irritating when benefit of hindsight results in "this would never have worked" statements. Of course not "all" RN forces would be found / attacked in time, let alone kept away from the invasion area, but the risk of losing major assets would have been real. Even if the invasion itself would fail, would a weakened RN still prevail in the Battle of the Atlantic? "What-if" is notoriously unreliable. We just don't know, not if the Germans would have tried, or if the RN would have risked engagement, given German air supremacy.
    – DevSolar
    Mar 7, 2017 at 12:20
  • @MAGolding: During the Battle of Britain, the RAF and Luftwaffe were consuming themselves at a rate where both would reach zero at about the same time (source: The Hardest Day, Price). Thus, a victory for the Luftwaffe (destroying the RAF) would have resulted in no air support of the landings, which was unacceptable. However, both sides were unaware of their comparative consumption rates until afterwards. Faulty score keeping and poor intelligence kept both sides from having a clear picture of what was going on while in the thick of it.
    – Smith
    Mar 7, 2017 at 15:15
  • I like the statement "The Allies were fussy..." It was a case of trying for optimum conditions while time afforded, but I also agree that there would have been no postponing much longer if the stars didn't line up. You couldn't trade optimum landing conditions against the remaining summer season for too long.
    – Smith
    Mar 7, 2017 at 15:19

The Germans may have faced the "same" weather difficulties across the English Channel as the Allies, but they didn't view them the same way.

The Allied invasion of Normandy was a highly sophisticated, professional operation, the most advanced of its time. Because of that, the Allies took very much to heart even slight variations in the weather conditions, and found only a few days in the year suitable for optimal operation.

On the other hand, German plans for "Sea Lion" were "jerrybuilt" (pun intended), in the manner of Goering, assumed that they could obtain air superiority over the English Channel (perhaps not), and 2) that such superiority would adequately deter British naval action, despite evidence in Norway to the contrary. So they made only the most elementary plans for crossing the English Channel, using civilian vessels such as barges, not specialized landing craft such as the Allies' LSTs. Under those circumstances, few worried about weather conditions over the English Channel.

  • No, actually it was not expected to be a cakewalk, not by Raeder and not by Hitler.
    – DevSolar
    May 19, 2017 at 10:04
  • @DevSolar: OK, removed the reference to "cakewalk." Of course, Raeder was one of those who didn't believe that, but I"m surprised that was true of Hitler, who thought the Soviet Union would fall in six months.
    – Tom Au
    May 19, 2017 at 12:52
  • If you take a closer look at Seelöwe, the "Führerweisungen" 16 and 17, and what we have in statements from the people involved, they knew that invading England was a long shot indeed. Basically, the hope was that the "credible threat" of Seelöwe would make the UK settle for an armistice. (After all, Hitler didn't want to conquer Britain, he wanted to be able to focus his forces on Russia.) If you e.g. check Weisung 16, you might note the wording -- "prepare and if necessary execute an invasion..."
    – DevSolar
    May 19, 2017 at 13:10
  • Also, they would not have just relied on air superiority. Mines, shore-bound artillery, engaging the RN in the North Sea and the Mediterranean...
    – DevSolar
    May 19, 2017 at 13:13

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