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Saxon thegn | Anglo Saxon History
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| Battle of Hastings 1066AD - A1 -Both Fleets, One Weather System |
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| The September Storm - Both Fleets, One Weather System |
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| | Introduction ▲ |
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The storm that struck William’s fleet as it left Dives-sur-Mer in September 1066 is documented on
page D —
Sailing, Dives sur Mer to St Valerie. That page establishes that the Norman fleet lost approximately
83 ships on the coastal run to St Valérie, that William suppressed news of the casualties, and that
the storm involved a counter-clockwise low pressure system tracking up the Channel.
This page proposes a wider meteorological model. The storm was not an isolated event. It was one
component of a larger, persistent atmospheric pattern — an Omega block — that
governed the entire campaign of September 1066.
That single pattern simultaneously:
- Guided Harald Hardrada’s fleet south from Norway to Yorkshire with following winds
- Trapped William’s fleet at Dives with persistent contrary winds for weeks
- Generated the counter-clockwise low that damaged both Harold’s and William’s fleets
in mid-September — from opposite sides of the same 25 miles of water
- Finally collapsed to produce the light southerly that carried William across on 27–28 September
Three invasions. Three fleets. One weather pattern. One outcome — the Norman Conquest of England.
This is a theoretical model. It has been submitted to the Met Office National Meteorological
Library for expert review. Comments from meteorologists or maritime historians are welcomed via the
contact page.
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| The Omega Block — The Master Pattern ▲ |
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An Omega block is a well-documented atmospheric configuration in which the jet stream splits around a
slow-moving or stationary high pressure ridge, with a low pressure system on each side. The pattern
takes its name from its resemblance to the Greek letter Ω. In the North Atlantic and European
region it can persist for days or weeks, fundamentally altering weather patterns across a large area.
The model proposed here places an Omega block over the British Isles and adjacent seas in August and
September 1066, configured as follows:
- Low 1 — a counter-clockwise low centred over or near the northern North Sea,
approximately in the region of Edinburgh or southern Norway
- High ridge — a slow-moving area of high pressure trapped between the two lows,
centred over central or southern England
- Low 2 — a counter-clockwise low developing in or tracking up the English Channel
Each component of this pattern affected the three fleets differently — determined entirely by
their position relative to the system.
| Component |
Fleet affected |
Position relative to component |
Wind produced |
Observed result |
| Low 1 (northern North Sea) |
Hardrada (Norse) |
Western flank of Low 1 |
Easterly then northerly — directly behind his sails |
Fast passage from Norway via Shetland and Orkney to Yorkshire |
| High ridge (central England) |
William (Norman) |
South of the high |
Northerly headwind in the Channel |
Trapped at Dives for weeks. Cannot sail against persistent northerly. |
| Low 2 (English Channel) |
Harold (English) and William (Norman) |
Harold on northern side; William on southern side |
South-easterly on English coast; north-westerly on French coast — simultaneously |
Both fleets damaged in mid-September. Two sources, one storm. |
| Block collapses; high drifts NE to Denmark |
William (Norman) |
Now south of the displaced high |
Light southerly at St Valérie |
William crosses 27–28 September in ideal conditions |
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| Low 1 — Hardrada’s Wind ▲ |
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Harald Hardrada assembled his fleet at Solund in the Sognefjord, Norway, and departed in early August
1066 with approximately 300 longships. His route took him west to Shetland, south to Orkney where he
collected the Jarls Paul and Erlend Thorfinnsson and additional forces, then south down the east coast
of Scotland and England to the Humber, and finally up the Ouse toward York.
This route requires explanation. The initial westward leg from Norway to Shetland requires an
easterly wind. A simple blocking high over northern England would not produce this —
it would produce southerlies on the eastern flank, which would be useless or contrary for a
westward passage. However, a counter-clockwise low centred over the northern North Sea or near
Edinburgh would produce exactly the easterly needed on its southern flank, shifting to a northerly
on its western flank as Hardrada turned south from Orkney.
This is the critical meteorological observation: Hardrada’s route implies Low 1, not a simple
high. The low gave him the easterly for the Norway-to-Shetland leg, then the northerly
for the Orkney-to-Yorkshire leg — following winds throughout.
| Route segment |
Direction of travel |
Wind required |
Produced by |
Historical speed |
| Solund (Norway) to Shetland |
West |
Easterly |
Southern flank of Low 1 |
c.10 days (est.) |
| Shetland to Orkney |
South-west |
North-easterly |
Western flank of Low 1 developing |
c.5–7 days (est.) |
| Orkney south down Scottish coast |
South |
Northerly — directly following |
Western flank of Low 1 |
Fast — square sails filled |
| Tynemouth to Scarborough to Holderness |
South |
Northerly — following |
Western flank of Low 1 |
c.200 miles in 5–6 days |
| Into the Humber estuary |
West (turning inland) |
Beam wind |
Transition zone |
Tacking up estuary |
The historical record confirms Hardrada’s remarkable speed. John of Worcester places him at Tynemouth
on 8 September. Orderic Vitalis places the fleet at the Humber on 18 September. Scarborough was burned
around 16 September. The fleet reached Riccall (8 miles south of York) around 18–19 September, and
fought the Battle of Fulford on 20 September. This rate of progress is consistent with persistent
following winds throughout the coastal passage.
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| The Trapped High — William’s Prison ▲ |
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Between the two lows, the Omega block configuration traps a high pressure ridge. Winds in the centre
of a high are characteristically light — the sinking air and slack pressure gradient produce calm
or gentle conditions at the surface. The high is slow-moving or stationary by definition.
For William, positioned south of this high on the Norman coast, the clockwise circulation of the high
produced a persistent northerly — exactly the headwind that prevented a crossing to England.
A sailing fleet of 700 vessels cannot beat north into a sustained headwind. William was effectively
imprisoned at Dives from early August until the block began to break down in mid-September.
The trapped high also explains a feature of the historical record that has puzzled historians: the
prolonged nature of the wait. William was not simply waiting for the wind to shift
direction. He was waiting for an entire large-scale atmospheric pattern to collapse. That is a
fundamentally different kind of wait — one that cannot be hurried, planned for, or predicted with
any accuracy from the beach at Dives.
It also explains why William prayed publicly at St Valérie for a change in the wind, and why
he granted a charter to the church there in thanks when it came. He would have understood, as any
experienced medieval sailor would, that the wind had been against him in a way that went beyond
ordinary bad luck. Something large was holding it in place.
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| Harold's Fleet — The English Side of the Storm ▲ |
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Harold had maintained a fleet watching the Channel from the Isle of Wight throughout the summer of 1066.
The Anglo-Saxon Chronicle records that the fleet was stood down around 8 September — the ships and men
had been at sea for months, supplies were exhausted, and the sailing season was considered to be ending.
The fleet was ordered back to London, its home base.
There is only one Chronicle reference to losses in Harold's fleet on this passage, so it
is shown in red as it is not corroborated:
The Anglo-Saxon Chronicle records that Harold's fleet suffered losses and damage on the return
voyage from the Isle of Wight to London. Ships were wrecked and men were drowned. The scale of
the losses was sufficient to be noted as a significant event, and it contributed to the weakening
of English naval capacity at a critical moment.
The route from the Isle of Wight to London covers approximately 200 to 250 miles. The fleet would
have moved east along the Sussex coast, past Beachy Head and the Seven Sisters, through the Strait
of Dover, around the North Foreland, and then south-west into the Thames estuary — a passage that
typically took three to five days depending on conditions and the size of the fleet.
Leaving around 8 September, Harold's fleet would have been somewhere between Beachy Head and the
Strait of Dover on approximately 10 to 12 September. This places the English fleet within
20 to 30 miles of the French coast at precisely the moment William's fleet was leaving Dives.
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| William's Fleet — The Norman Side of the Storm ▲ |
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William left Dives-sur-Mer on approximately 12 September 1066, heading north-east for
St Valerie-sur-Somme — a coastal passage of around 150 miles. As documented on page D,
the fleet suffered significant losses and damage on this leg. William of Poitiers records
that William concealed the drowned and buried them in secret to prevent panic. The ship count
discrepancy between the Dives ship list (777 vessels) and Master Wace's figure for St Valerie
(694 ships) implies approximately 83 ships were lost.
The timing is precise: William was at sea in deteriorating conditions on 12 to 14 September.
Harold's fleet was at sea in the same Channel on 9 to 13 September. The overlap is direct.
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| The Reconstructed Timeline ▲ |
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Placing both fleets on a single timeline reveals the proximity of the two events and
makes the case for a shared weather system:
| Date |
Harold's Fleet (English) |
William's Fleet (Norman) |
| 8 Sept |
Fleet stood down at Isle of Wight. Departs east for London. |
Still at Dives. Waiting for favourable wind. |
| 9–10 Sept |
Rounding Beachy Head, heading east along Sussex coast. |
Final preparations at Dives. |
| 10–11 Sept |
Approaching Dover Strait. Within 20–30 miles of French coast. |
William preparing to depart. Storm building. |
| 12–13 Sept |
Fleet in Strait or Thames approaches. Storm damage and losses recorded. |
William departs Dives. Fleet immediately hit by storm. Losses on Alabaster Coast. |
| 13–15 Sept |
Battered fleet enters Thames, arrives London. |
Surviving ships reach St Valerie. William suppresses casualty news. |
| 15–27 Sept |
Harold receives news of Hardrada. Rides north. |
William waits at St Valerie for favourable wind and replacement supplies. |
| 25 Sept |
Battle of Stamford Bridge. Hardrada defeated. |
Still at St Valerie. |
| 27–28 Sept |
Harold hears of William's landing. Begins march south. |
Wind shifts southerly. Fleet crosses Channel. Lands at Pevensey. |
| 14 Oct |
Battle of Hastings. |
The overlap on 12 to 13 September is the critical window. Both fleets were at sea simultaneously.
Both suffered losses. Both were in the same body of water, on opposite sides of what the meteorological
evidence suggests was the same low pressure system.
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| Prof Licence and the Sea Voyage Theory ▲ |
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In 2026, Professor Tom Licence of the University of East Anglia published research arguing that
Harold's famous 200-mile march from York to Hastings never happened — that Harold returned from
Stamford Bridge to London largely by sea, using the fleet that had gathered at the Humber,
which included the approximately 300 vessels captured from Harald Hardrada's Norse army.
Prof Licence argues that the Anglo-Saxon Chronicle phrase describing Harold's ships as having
"come home" was misread by Victorian historians as a disbanding of the fleet. He contends the
ships remained operational and were used for Harold's return south, for a naval blocking action
against William, and possibly even for a sea engagement near Hastings.
This is an important revision and the evidence he presents for the fleet remaining active is
persuasive. However, the sea voyage theory raises a meteorological problem that Prof Licence
does not address.
If the September storm was the same system that damaged William's fleet — and if, as the
counter-clockwise rotation model suggests, that storm was producing south-easterly winds on
the English side of the Channel — then Harold sailing south from the Humber in mid to late
September would have been heading directly into the wind that was simultaneously filling
William's sails at St Valerie.
The wind that gave William his crossing on 27 to 28 September was a southerly. Harold, coming
south down the North Sea coast, would have been sailing into that same southerly — making the
sea voyage slow, dangerous and exhausting for ships already weakened by the earlier storm.
This may explain why, if Harold did use the fleet for the return south, the operation was slower
than the overland alternative would have been, and why — as Prof Licence himself notes — the
English fleet arrived too late to prevent William's landing and may have been unable to mount
an effective blocking action.
The storm does not disprove Prof Licence's theory. It may, however, be the missing explanation
for why Harold's sophisticated naval strategy ultimately failed to deliver the decisive
interception he intended.
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| Implications ▲ |
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If the same low pressure system struck both fleets simultaneously in mid-September 1066,
several previously puzzling aspects of the campaign fall into place:
Why Harold stood down his fleet on 8 September. The decision has often been
criticised as premature. But if a major storm was already building in the western Channel,
Harold's commanders may have had good reason to get the fleet moving before conditions
deteriorated further. The timing was not poor judgement — it was a race against the weather
that was nearly won.
Why William's wait at St Valerie was so prolonged. The received explanation
is that William was simply waiting for a southerly wind. But as page D argues, he was also
waiting for replacement supplies — the lost ships were predominantly the non-oared transport
and supply vessels. The storm that drove him to St Valerie left him with most of his army
but insufficient food and fodder for an invasion. He needed both the wind and the supplies
before he could sail.
Why the two fleets never met in the Strait. Harold's fleet was in the Strait
of Dover on approximately 10 to 12 September — the closest point of approach between England
and France, the natural interception point for any blocking action. William was still at Dives.
Had Harold known, or had the weather been different, the two fleets might have met there.
Instead, Harold's fleet was driven through the Strait by the building storm, and William left
Dives into that same storm two days later — the two forces passing each other's position
separated by a day and 25 miles of open water.
Why neither side recorded the connection. Norman chroniclers were writing
about William's campaign. Saxon chroniclers were writing about Harold's. Neither had reason —
or possibly knowledge — to connect the two sets of losses. The Norman sources actively suppressed
the storm damage. The connection between the two events has therefore remained invisible for
nearly a thousand years, simply because nobody was reading both sets of sources simultaneously
and asking whether the weather linking them was the same weather.
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| Conclusion ▲ |
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The meteorological, geographical and chronological evidence is consistent with a single counter-clockwise
low pressure system sitting over the Strait of Dover in mid-September 1066, producing north-westerly
conditions on the French side that wrecked William's supply ships on the Alabaster Coast, and
south-easterly conditions on the English side that drove Harold's fleet onto a lee shore in the
Thames approaches.
Both fleets were at sea simultaneously. Both suffered losses. Both were in the same Channel,
separated by 20 to 30 miles of water, on opposite sides of the same rotating weather system.
One storm. Two fleets. One outcome — the Norman Conquest of England.
The storm did not simply delay William. It weakened Harold's naval capacity, disrupted his
ability to maintain a blocking force in the Strait, drew both armies into the sequential
crises — Hardrada in the north, William in the south — that ended at Hastings on 14 October 1066.
This theory invites further examination by maritime historians and meteorologists. The author
would welcome contact from anyone able to model Channel storm tracks for September 1066 using
palaeoclimatological data.
e weather linking them was the same weather.
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| Bibliography ▲ |
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Primary Sources
- Anglo-Saxon Chronicle — multiple manuscript versions, see
page 1, Anglo Saxon Chronicles
- William of Poitiers, Gesta Guillelmi — the only contemporary Norman account of
the storm between Dives and St Valerie
- Master Wace, Roman de Rou — ship count at St Valerie (694 ships)
- Domesday Book and Annales Altahenses — references to a possible English sea
engagement, October 1066
Secondary Sources
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Local Interest
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