How to Read Wind and Weather Before a Sailing Day

Wind does not care about your itinerary. It does not care that you booked a week in the Cyclades or that the crew voted for a beach 30 NM south. Reading a weather forecast accurately, and then making honest decisions based on what it says, is the single most important skill any sailor can develop.

The good news: it takes about 5 minutes each morning. The better news: modern forecasting tools are remarkably accurate up to 48 hours out. This guide covers everything from the Beaufort scale to regional wind patterns, so you can step aboard with confidence. If you are new to sailing terminology, our sailing lingo guide covers the basics.

The Beaufort Scale: Your Daily Reference

Admiral Sir Francis Beaufort standardised this scale in 1805. More than two centuries later, it remains the fastest way to translate a number into what you will actually experience on deck. Here is what each force means on a typical 40ft charter yacht.

Force	Knots	Sea Description	Feel on a 40ft Yacht	Recommendation
F0	0 to 1	Mirror-flat, glassy	No sailing. Motor only. Hot and still.	Go (motor)
F1	1 to 3	Ripples, no crests	Sails barely fill. Very gentle.	Go
F2	4 to 6	Small wavelets, glassy crests	Light sailing. Pleasant for everyone.	Go
F3	7 to 10	Large wavelets, crests begin to break	Ideal. Boat moves well, crew comfortable.	Go
F4	11 to 16	Small waves, frequent whitecaps	Good sailing. Heeling noticeable. Some spray.	Go
F5	17 to 21	Moderate waves, many whitecaps	Lively. Beginners may feel uneasy. Reefing wise.	Caution
F6	22 to 27	Large waves, white foam crests	Hard work. Gear sliding. Short passages only.	Caution
F7	28 to 33	Sea heaps up, foam streaks	Uncomfortable and potentially dangerous.	Stay
F8	34 to 40	Moderately high waves, spindrift	Dangerous for charter yachts. No question, stay.	Stay

Force 3 to 4 is the sweet spot for most holiday crews. If you are sailing with children or total beginners, aim for F3 or below. For more on risk assessment, read our honest look at sailing safety.

Where to Check the Forecast

No single source tells the whole story. Use at least two, and cross-reference with local information.

Windy.com (free)

The best visual tool available. Animated wind maps show speed, direction, and gusts overlaid on your exact route. Toggle between forecast models, ECMWF and GFS, and look for agreement between them. If they disagree significantly, treat the worse forecast as more likely. The mobile app works offline once data is cached.

PredictWind (from EUR 8/month)

Built specifically for sailors. It offers departure planning tools, offshore routing, and hyper-local coastal forecasts that generic apps miss. The "departure board" feature tells you the best window to leave harbour. Professional skippers swear by it.

Local and regional sources

• Croatia: Prognoza.hr (DHMZ). Also listen for the "Upozorenje" (warning) on VHF Channel 67 or 73, broadcast three times daily by the harbourmaster.
• Greece: Poseidon system (poseidon.hcmr.gr). Detailed Aegean wave and wind forecasts. Essential during Meltemi season in August.
• Spain: AEMET (aemet.es). Coastal bulletins for the Balearics, Canaries, and mainland coasts. See our Spain sailing guide for details.
• Turkey: The Turkish Met Office (mgm.gov.tr) publishes coastal forecasts. Marina staff in Gocek and Fethiye are typically well-informed. See our Turquoise Coast route guide.

VHF weather bulletins

Every maritime nation broadcasts weather on VHF radio. In the Med, listen on Channel 68 (Greece) or Channel 67/73 (Croatia) at scheduled times, usually 0600, 1200, and 1800 local time. Your charter briefing should tell you the exact channel and schedule. Write the forecast down. Memory is unreliable when the wind picks up.

What to Look For in a Forecast

Opening a weather app is not the same as reading it. Here are the five things to check, in order of importance.

1. Wind direction

Direction determines which side of an island is sheltered and which is exposed. A NW wind in Croatia makes the eastern side of the islands calm while the western coasts become uncomfortable. Plan your anchorage accordingly.

2. Wind speed: average and gusts

The average tells you the baseline. The gusts tell you the peaks. A forecast of 15 knots average with gusts to 25 is very different from a steady 15. Always plan for the gust figure, not the average. If gusts exceed F6, think hard before leaving.

3. Trend over the day

Wind often builds through the afternoon and drops at night. In the Mediterranean, thermal winds typically peak between 1400 and 1700. Leave early if you want a gentle sail. By noon you may be looking at a completely different wind picture.

4. Sea state and wave height

Wind speed alone does not describe comfort. A 20-knot wind blowing over open water for 200 NM creates bigger waves than the same wind in a sheltered channel. Check wave height separately. Anything above 2 metres is uncomfortable for most charter crews. Above 3 metres, even experienced sailors will be working hard.

5. Clouds

This is the one thing apps cannot fully capture. Look up. Towering cumulonimbus clouds, the anvil-shaped ones, signal thunderstorms, which bring violent gusts that can exceed 50 knots with almost no warning. Dark, low, fast-moving clouds from one direction while surface wind comes from another? That is a sign of an approaching front. Get to shelter.

Regional Winds Every Sailor Should Know

Each sailing ground has its own wind personality. Learn the local names before you arrive.

Maestral (NW, Croatia and Italy)

The friendly one. A thermal sea breeze that fills in around midday and blows F3 to F5 through the afternoon. It is the engine of summer sailing in the Adriatic. Predictable, warm, and usually gone by sunset. If you are planning a Split to Dubrovnik route, the Maestral will be your most frequent companion.

Meltemi (N, Aegean Greece)

The powerful one. A dry northerly that blows F4 to F7 from June to September, peaking in July and August. It funnels between islands, accelerating in channels. The Meltemi can make the Cyclades genuinely challenging. Our Athens to Mykonos route accounts for it. Beginners should consider the Ionian instead, where the Meltemi does not reach.

Bora (NE, Croatia)

The dangerous one. A cold, violent katabatic wind that pours down from the mountains, often exceeding F7 with gusts to F9 in narrow channels. It arrives fast, sometimes with little warning in winter and shoulder seasons. The Bora is the main reason off-season Adriatic sailing demands serious respect. In summer it is rare but not impossible.

Sirocco (SE, Mediterranean-wide)

The warm, wet one. A southerly wind carrying Saharan air and rain. It builds slowly over 24 to 48 hours, which gives you time to prepare, but it brings poor visibility and an uncomfortable swell. Sea state deteriorates before the wind fully arrives, and that catches people out.

Trade winds (E, Caribbean)

The consistent one. Easterly winds of F4 to F5 blow reliably from November to June, making the BVI and wider Caribbean superb sailing grounds. The main risk is not the trades themselves but tropical weather systems, particularly from June to November.

Making the Go or Stay Decision

Reading the weather becomes a skill rather than a task at this point. Numbers alone do not make the decision. Context does.

The framework

• F3 to F4 (7 to 16 knots): Ideal. Go. Enjoy.
• F5 (17 to 21 knots): Fine for experienced crews. First-timers should shorten the passage or choose sheltered routes.
• F6 (22 to 27 knots): Short passages only, with a clear plan and shelter options. Reef before leaving.
• F7+ (28+ knots): Stay in harbour. No exceptions for charter yachts. Explore the town, find a taverna, read a book. The sea will still be there tomorrow.

Other factors that shift the line

Wind is not the only variable. A 16-knot wind, the top of F4, combined with a 2.5-metre swell from a different direction creates confused seas that feel much worse than F5 in flat water. Short passages of 5 to 10 NM between sheltered islands are manageable in conditions that would be miserable over 30 NM of open water.

Crew experience matters enormously. If you have seasick-prone passengers, see our seasickness guide and drop your comfort threshold by one Beaufort level.

One rule is non-negotiable: the skipper decides, not the passengers. Social pressure to "just go" has caused more problems at sea than any weather system. If your skipper says no, trust the call. A good skipper who keeps you in harbour on a rough day is worth more than a reckless one who gives you a story you never wanted.

When Weather Changes Mid-Passage

Forecasts are good, but they are not perfect. Conditions can shift faster than predicted, especially near mountainous coasts or in island channels. Here is what to do.

Reef early

If you think you might need a reef, you already need a reef. Reducing sail area when the wind is still manageable is ten times easier than fighting with flapping canvas in 25 knots. On a charter yacht, the first reef typically goes in around 18 to 20 knots apparent. Our RYA Day Skipper guide covers sail handling and other techniques in detail.

Know your nearest shelter

Before every passage, identify at least two bail-out harbours or anchorages along your route. If the wind shifts, head for the one that is now on your lee. Do not press on to the original destination out of stubbornness.

Do not panic

A modern charter yacht is built to handle far more than its crew can comfortably tolerate. The boat is not going to sink in F6. It will be uncomfortable, wet, and noisy, but structurally fine. Slow down, bear away if possible, and work towards shelter methodically.

Use VHF Channel 16

If you genuinely need help, call on VHF Channel 16. This is the international distress and calling frequency. State your vessel name, position, number of persons on board, and the nature of your problem. Do not wait until the situation is critical to make the call. Asking for advice early is seamanship, not weakness.

After the blow

Once sheltered, check everything: rigging, deck fittings, anchor gear, and crew welfare. Strong wind days are tiring even when nothing goes wrong. Give your crew time to recover before the next passage. Sometimes the best decision after a rough afternoon is to stay put for an extra day. Your holiday is still your holiday, even if the chart changes.

Weather reading is a habit, not a talent. Five minutes every morning with a coffee and a phone screen will keep you safe, comfortable, and in the right anchorage at the right time. Build the routine on your first charter and by your third trip it will feel as natural as checking the fuel gauge before a road trip. On your first morning out, the 0600 VHF bulletin and a quick look at Windy is all it takes.