A marine forecast is a handful of numbers and a few words. On a small boat the numbers that matter are easy to mix up, and mixing them up is how a moderate day becomes a wet one. This page explains the words the Adriatic forecasts use, and how the live board on Navigate Boats turns them into a verdict for your own boat. It is not a forecast. Today’s weather is the board, and the official services linked below.
Wind at sea is given in knots. One knot is one nautical mile an hour. A forecast that says metres per second is the same wind in another unit. Roughly, multiply metres per second by two to get near the knots, and do not navigate on that rough sum: read the number in the unit the forecast actually used. The board asks Open-Meteo for the wind in knots, so the figure on the page is already in the unit sailors use.
The average, or the mean, is the wind the forecast expects as a sustained speed. It is the number people quote. It is not the number that heels a light boat. That number is the gust.
A gust is a short peak. On the Adriatic it is often much higher than the mean, especially in the Bura, which is a fall wind. The board shows the gust beside the average on purpose, so a gusty day cannot hide behind a moderate mean. If the gust forecast is far above the mean, treat the day as a gust day even when the headline number sounds comfortable. Open boats and RIBs feel that gap more than a heavy yacht does.
Beaufort is the old scale of wind force, from calm to hurricane, still used because the words match what you see. The usual steps, which this site’s own scale follows, put force 4 near 11 knots, force 6 near 22 knots and force 8 near 34 knots, with the force rising as the knots rise. Force 4 is a moderate breeze. Force 6 is a strong breeze. Force 8 is a gale. These are descriptions of the wind, not a law about your boat. No national service publishes one knot value that is “safe” for every small boat. What they publish are warnings. In Croatia, DHMZ issues wind warnings, and the board will not give a better verdict than the warning for your area allows. In Slovenia, read ARSO. In Montenegro, read the national hydrometeorological service.
Wave height in a forecast is the height of the waves the wind and the swell are producing, not the height of every single ripple and not the height of the worst wave you will meet. A moderate wind with a long fetch, which is what the Jugo has along the Adriatic, builds a larger sea than the same wind blowing off the land. Swell can arrive before the wind does, and it can remain after the wind has dropped. A forecast that gives only wind speed is unfinished. Look for a wave or sea-state line, and look at the period if it is there: a long period is a longer, heavier sea than a short chop of the same height.
The board reads the marine forecast’s wave height into the verdict. A day with a modest wind and a large sea can still be a no-go for a small open boat. That is the point of having both numbers.
Direction is where the wind comes from. A north-easterly on this coast is the Bura. A south-easterly is the Jugo. A summer north-westerly that builds in the afternoon is the Maestral. The name tells you the character: gusts, or a building sea, or a breeze that dies in the evening. The board names those three when the direction and the conditions match. The names are local language, not a different wind.
Read the official forecast first. Then set your boat on the board and see whether that forecast is a go for the size and type you actually have, with or without children aboard. If the two disagree, believe the more cautious one, and believe a warning over both. The go/no-go guide is the habit that sits on top of these numbers. The season guide is the shape of the year, not the shape of today.
Check today’s go/no-go for your boat
These guides describe typical patterns, not today’s weather. Navigate Boats is a planning aid, not a navigation tool: before you go, check the official marine forecast and warnings from DHMZ (Croatia), ARSO (Slovenia) or the Montenegrin hydrometeorological service, and use your own judgement.
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