Older accounts of when to sail treat the Mediterranean as a summer region, place Svalbard in Greenland, and sort cruises into short, standard and long as though those were categories somebody defines. None of the three survives checking. October is the single busiest month in Mediterranean cruise ports, ahead of July and August, so the case for the shoulder season rests on heat rather than on quiet. Svalbard is Norwegian, and its midnight sun runs from 20 April to 22 August. And no standard definition of cruise length exists anywhere — not in the United Nations recommendations on tourism statistics, not in the Department for Transport's figures, not in the travel trade body's own reporting.
The Atlantic hurricane season, and what actually closes a port
The North Atlantic hurricane season officially runs from 1 June to 30 November, and its peak falls in a three-month window, August to October, which carries the great majority of tropical storms and hurricanes. A single peak date is often quoted alongside those months; the three-month window is what the forecasting agency actually states, and it is the safer thing to rely on.
The mechanism behind a changed itinerary is more useful than any adjective about risk. Ahead of gale-force winds the United States Coast Guard sets escalating port conditions: Whiskey at 72 hours, X-Ray at 48, Yankee at 24 — at which the port is restricted and traffic control measures apply — and Zulu at 12, at which the port is closed to all vessel traffic except movements specifically authorised. A ship cannot enter or leave a closed port, which is why calls are dropped and substituted at short notice rather than whole cruises cancelled.
None of which closes the region. The Caribbean is the largest cruise destination in the world, with 16.27 million passengers in 2025, and it sails the whole year round. What the season does is thin the traffic: September is traditionally the slowest month for Caribbean arrivals, and in the severe season of 2017 September arrivals fell by about 20 per cent before recovering to 2 per cent growth in October.
Alaska: a short season, and the weather is not where it is expected
Alaska has the hardest season boundary of any cruising region, and it is set by regulation rather than by weather. Federal rules for Glacier Bay admit a maximum of two cruise ships a day, with a quota of up to 184 cruise ship entries between 1 June and 31 August and up to 122 entries across May and September. For that purpose a cruise ship means a motor vessel of at least 100 gross tonnage domestically, or 2,000 internationally, certificated to carry more than twelve passengers for hire. Permits are required of all vessels from 1 June to 31 August, and the park runs radio check-in from 1 May to 30 September. The effective season is therefore May to September, with the core in June, July and August.
The weather advice that usually accompanies that season is wrong, and the national weather service office at Juneau says so. It puts the best weather window at April through to early July, calls March to June the dry season, and names April the driest month, at about 70 mm. Cloud and the chance of precipitation rise after mid-July. October is the wettest month, with nearly a 70 per cent chance of rain on any given day. June and July have the fewest windy days, though gales are possible in any month. In south-east Alaska the late season is wetter, not better.
The Mediterranean sails all year, and October is its busiest month
On the Mediterranean cruise ports' own statistics for 2023, May to October accounted for 73.2 per cent of passenger movements and 70 per cent of calls. But the single highest month for passengers was October, at 13.84 per cent, and for calls October again, at 14.28 per cent — ahead of July on 12.58 per cent, and August and September on 12.18 per cent each. The lowest month was February, at 2.39 per cent of passengers and 2.28 per cent of calls, and the winter does not stop: January, February, March and December together carry roughly 12 per cent of passengers.
That matters because the shoulder season is usually recommended on the grounds that it is quieter. In the Mediterranean it is not. The case for it is heat, and that case is strong. Two heatwaves in June 2025 produced very strong heat stress across western and southern Europe, with parts of Portugal reaching extreme heat stress and apparent temperatures of up to 48°C; western Europe recorded its warmest June on record at 20.49°C; and the western Mediterranean recorded its highest ever June daily sea surface temperature on 30 June 2025, at 27.0°C, some 3.7°C above average. The ports themselves report a deliberate shift towards extending the season and spreading arrivals more evenly across the year — a push reinforced by the caps and terminal reductions several of them have adopted since.
Norway: the midnight sun and the aurora cannot both be had
The two reasons people sail to northern Norway are mutually exclusive by definition. The midnight sun makes the aurora invisible, and the aurora needs dark nights.
Midnight sun dates, from the national tourist board:
- Svalbard — 20 April to 22 August
- North Cape — 14 May to 29 July
- Tromsø — 20 May to 22 July
- Lofoten — 28 May to 14 July
- Bodø — 4 June to 8 July
- The Arctic Circle — 12 June to 1 July
Svalbard is Norwegian, not Greenlandic, and its season is the longest of the six because it lies the furthest north. Older accounts place it in Greenland.
The aurora, on the account of the geophysics department at Tromsø, is visible in northern Norway from about the beginning of September to the middle of April, most commonly from early evening into late night. The lights are present all year; they cannot be seen when the nights are light.
For the fjords themselves no single official season is declared. Summer is the busiest time, with packages running May to September, while northern-lights itineraries run from roughly September or November through to March.
Antarctica: a longer season than its reputation
Antarctica is usually described as having a narrow window. It does not have one. The 2025–26 landing season ran from 19 October 2025 to 1 April 2026 — about 164 days, five and a half months, austral spring through to autumn — with roughly 85,195 landed passengers across 539 voyages, 3,425 landings at 206 sites, from 47 vessels.
Who controls access is also widely misstated. Access is governed by the Antarctic Treaty System and the protocol on environmental protection, implemented through national permitting authorities — a British-based operator needs a British permit. The industry association that publishes the season figures is an association of tour operators, not a regulator, and its code of conduct and site guidelines bind its own members.
The familiar hard limits deserve care. The rule that vessels carrying more than 500 passengers may not land, and that smaller vessels may put no more than 100 passengers ashore at once with one guide for every twenty, comes from a treaty measure of 2009 whose status is recorded as not yet effective. It takes effect only once every party whose approval is required has given it, and Brazil, China, Germany, India, Italy and the United States have not. Those limits are therefore observed in practice by association members rather than enforced by an instrument in force.
Northern Europe and the British Isles
The Met Office defines meteorological summer as 1 June to 31 August, while astronomical summer runs from about 21 June to about 22 September. July is usually the warmest month and June the sunniest; summer is also the most thundery season; the 1991–2020 mean summer temperature was 14.59°C.
For anyone sailing without flying, the choice of departure port is heavily concentrated in Southampton. The United Kingdom and Ireland sent 2.54 million people on an ocean cruise in 2025, a record, and their destinations divide as Mediterranean 34.5 per cent, northern Europe 27.2 per cent and the Caribbean 13.7 per cent — the last of those up 12 per cent in a year. The average cruise length was 9.6 days, and seven-night sailings made up 44 per cent of the total.
Rivers have a closed season that the sea does not
European river cruising runs on 408 active vessels and 60,702 berths, carrying 1.39 million passengers in 2024, up 14 per cent. Nearly three-quarters of the fleet works the central European waterways — the Rhine, the Main, the Main–Danube Canal, the Danube and the Elbe–Oder — and the Rhine with its tributaries, together with the Danube, carries most of the passengers, well ahead of the French rivers and the Douro.
Typical lengths are stated plainly in the navigation commission's own figures. Upper Danube cruises between Passau and Budapest last five, seven or eight days, while a voyage from south of Budapest to the Danube delta takes fourteen — a route whose traffic has fallen because of the war in Ukraine.
The structural difference from the sea is the thing worth knowing. An ocean ship reroutes around weather. A river ship cannot pass a drained lock. German waterway authorities bundle lock maintenance into a single annual window: for 2026 the Main–Danube Canal and Danube structures are closed to traffic from 7 to 27 March, twenty-one days, with five locks between Bad Abbach and Forchheim drained. The authority sets that timing two years in advance, in coordination with the shipping industry, precisely to limit disruption on the Rhine–Danube route.
Low water is the other constraint, and it works the opposite way about — unpredictably, and in high summer. Low water in July and August 2022 impaired Rhine navigation, and the commission expects longer periods of impaired navigation in the relevant Rhine sections. No official source quantifies how many river sailings have been shortened or replaced by coach as a result, so it is better treated as a structural risk than as a statistic.
How long is a cruise? No official answer exists
Short break, standard cruise, long cruise, world cruise: none of these is defined by anybody. Three independent checks say so.
The United Nations recommendations on tourism statistics, which are the global standard, contain no classification of cruises by length at all. Cruise passengers appear only as a case within same-day visitors, and cruising appears as a leisure purpose and as a minor group within waterway transport. The generic trip-duration bands run from same-day trips of no nights through one to three, four to seven, eight to fourteen, fifteen to twenty-eight, twenty-nine to ninety-one, and ninety-two to three hundred and sixty-five nights.
The Department for Transport defines a cruise by where passengers board and leave, not by how long it lasts, and sets no minimum duration and no itinerary requirement for either international or domestic cruises.
The travel trade body publishes an average rather than categories: a global average duration of 7.0 days in 2025, with North America on 6.71 days and exploration itineraries just under thirteen. European passengers take longer cruises than the average and Asian passengers the shortest. The only length-based term defined anywhere in the trade is a mini cruise, given as a typical duration of two to four nights with one or two ports of call.
So the figure that means something is the average — seven days globally, a little under ten for British and Irish passengers — and the bands above are general tourism-statistics bands, not cruise categories, and should not be read as though they were.
Dates to watch
Season dates are set annually and move a little. The Antarctic landing season is published each year by the operators' association. The annual lock closure on the Main–Danube Canal and the Danube is fixed two years in advance, so the 2027 and 2028 windows are already determined. Santorini's daily passenger cap was set for the 2025 and 2026 seasons only and will need renewing. And the Mediterranean ports report a continuing effort to lengthen the season at both ends, which over several years would flatten the October peak rather than move it.
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