When the meltemi blows: Greek sailing wind risk by month
When the meltemi peaks, and how many strong-wind days the Cyclades and the Ionian get each month (NASA data, our count). For choosing a Greek charter week.
Meltemi peak
mid-Jul–mid-Aug
peer-reviewed study
Source: Tyrlis & Lelieveld, Journal of the Atmospheric Sciences, checked
Checked
29 Oct 2026
study dates, our counts
The meltemi (the Etesian winds) is a persistent summer northerly over the Aegean, and its outbreaks are most frequent from mid-July to mid-August (peer-reviewed study, Tyrlis & Lelieveld 2013); at our Syros point in the Cyclades, days reaching force 6 (22 kn or more) average 4.9 in July and 4.7 in August, against 0.0 and 0.0 at Lefkada in the Ionian (our calculation from NASA POWER, 2016–2025). For lighter summer sailing the Ionian is the calmer choice in this data; the numbers are grid-cell means, not gusts, so plan sheltered alternatives and ask your base about the forecast each morning.
Checked 29 Oct 2026. Official dates are quoted; counts are our calculation from NOAA and NASA data (how we count); facts are labelled official, secondary or not verified (labels).
When the meltemi blows
- [Peer-reviewed study, not a government source] "The Etesians are persistent northerly winds that prevail over the eastern Mediterranean during summer." "Consistent with the monsoon influence, Etesian outbreaks are most frequent from mid-July to mid-August." The meltemi is the Greek name for the Etesians (Tyrlis & Lelieveld 2013, Journal of the Atmospheric Sciences; peer-reviewed study, not a government source). (Tyrlis & Lelieveld, Journal of the Atmospheric Sciences)
- [Peer-reviewed study, not a government source] A negative trend in the incidence of Etesian outbreaks is detected over the overall June–September period, "strikingly strong for September but diminishes in June" (Tyrlis & Lelieveld 2013; ERA-40 reanalysis; peer-reviewed study, not a government source). (Tyrlis & Lelieveld, Journal of the Atmospheric Sciences)
Our calendar marks July (from mid-July) and August (to mid-August) as the meltemi peak, our mapping of the study's words. When to go, with prices and the best months: best time to charter in Greece. This page prints no prices and no best-month verdict.
Cyclades or Ionian? Days per month reaching force 6 (22 kn or more), mean over 2016–2025 (our calculation from NASA POWER, checked 29 Oct 2026). Syros (Ermoupoli) is our Aegean point; Lefkada is the Ionian reference point. July and August in bold.
| Point | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Syros (Cyclades) | 9.6 | 9.3 | 7.4 | 3.7 | 1.9 | 1.4 | 4.9 | 4.7 | 4.7 | 3.9 | 4.6 | 6.9 |
| Lefkada (Ionian) | 0.7 | 0.3 | 0.6 | 0.2 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.1 | 0.8 | 0.2 |
Our Ionian 7-day route sits around Lefkada; the Cyclades route sails from Lavrio via Kea, Kythnos, Serifos, Sifnos and Antiparos to Syros (both routes).
Month by month
| Month | Meltemi peak (study) | Syros force 6+ days | Syros northerly share of those days | Syros mean wind (kn) | Lefkada force 6+ days | Lefkada mean wind (kn) |
|---|---|---|---|---|---|---|
| January | – | 9.6 | 58% | 14.0 | 0.7 | 8.1 |
| February | – | 9.3 | 70% | 13.6 | 0.3 | 7.9 |
| March | – | 7.4 | 72% | 12.6 | 0.6 | 7.2 |
| April | – | 3.7 | 76% | 10.4 | 0.2 | 6.5 |
| May | – | 1.9 | 84% | 9.3 | 0.0 | 5.9 |
| June | – | 1.4 | 93% | 9.9 | 0.0 | 5.5 |
| July | Meltemi peak (from mid-July) | 4.9 | 100% | 13.1 | 0.0 | 6.0 |
| August | Meltemi peak (to mid-August) | 4.7 | 100% | 13.4 | 0.0 | 5.5 |
| September | – | 4.7 | 98% | 12.5 | 0.0 | 6.1 |
| October | – | 3.9 | 97% | 12.0 | 0.1 | 6.4 |
| November | – | 4.6 | 61% | 12.4 | 0.8 | 8.1 |
| December | – | 6.9 | 71% | 13.2 | 0.2 | 7.5 |
Northerly share = force 6 days whose daily mean wind came from 315° to 45° (our choice), a proxy for the meltemi, not an observed outbreak (our method). "–" = no force 6 days that month. Not gusts.
What the official sources say
- [Peer-reviewed study, not a government source] "The Etesians are persistent northerly winds that prevail over the eastern Mediterranean during summer." "Consistent with the monsoon influence, Etesian outbreaks are most frequent from mid-July to mid-August." The meltemi is the Greek name for the Etesians (Tyrlis & Lelieveld 2013, Journal of the Atmospheric Sciences; peer-reviewed study, not a government source). (Tyrlis & Lelieveld, Journal of the Atmospheric Sciences)
- [Peer-reviewed study, not a government source] A negative trend in the incidence of Etesian outbreaks is detected over the overall June–September period, "strikingly strong for September but diminishes in June" (Tyrlis & Lelieveld 2013; ERA-40 reanalysis; peer-reviewed study, not a government source). (Tyrlis & Lelieveld, Journal of the Atmospheric Sciences)
We could not open an official Greek page on the meltemi (the Hellenic National Meteorological Service site failed to load for us), so the months come from a peer-reviewed study and the day counts are our calculation.
If the weather turns
- Emergency (ambulance, fire, police): 112, according to UK government travel advice, which adds: "Calling 999 from a UK mobile in Greece will automatically transfer you to the Greek emergency services." (UK FCDO (GOV.UK))
- 112 is available everywhere in the EU, free of charge, from fixed and mobile phones (European Commission). (European Commission)
- [Not verified] Hellenic Coast Guard number: the official page returned an error to us, so we give no number.
- 7-day sailing itinerary in Greece
- 7-day sailing itinerary in Greece: the Cyclades from Lavrio
- We opened no official forecast page for this area, so we link none.
Cancellation, insurance and weather guarantees
Booking in a risk season? Read your charter contract's weather and hurricane clauses: what happens if a named storm or a port closure stops you sailing, and whether you get a refund, a credit or new dates. Some booking platforms and charter companies sell cancellation options or a "weather guarantee", and some travel insurance covers trip cancellation or cutting a trip short because of weather; check what triggers the cover. We have no insurance partner and do not recommend a product. See our affiliate disclosure.
See boats in Greece
See catamarans for rent in Greece on SamBoat
Ask the operator about its weather and hurricane policy before you book; listings and prices on SamBoat are SamBoat's own. We may earn a commission if you book through our links, at no extra cost to you (disclosure).
How we count
Strong-wind days: from NASA POWER's daily WS10M_MAX (the highest hourly mean 10 m wind of the day in one grid cell), converted to knots (1 m/s = 3600/1852 kn), we count the days per month at or above 17 kn (Beaufort force 5, fresh breeze) and 22 kn (force 6, strong breeze), the lower limits on the Met Office scale, as a mean per month over 2016–2025. Direction shares use the day's mean wind direction (WD10M) in 45° bins. Our calculation.
Rain: NASA POWER's monthly corrected precipitation (PRECTOTCORR, mm/day) times the days in each month, averaged over 2016–2025, whole millimetres. Our calculation, not a rain-gauge normal.
Calendar: a month is marked if any part of it falls in the source's window (our mapping). "Mid-July", "the cold part of the year" and similar are the source's words.
Constants: strong-wind thresholds 17 kn (force 5) and 22 kn (force 6), years 2016–2025, 45° direction bins, NASA POWER API v2.10.1.
Weather data obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) Project, funded through the NASA Earth Science Division (pulled 29 Oct 2026) (NASA POWER, checked 29 Oct 2026). We changed the data: we counted days above thresholds, binned wind directions and summed daily rain into months (our calculation). Mean wind: NASA POWER monthly means, as on our other pages.
- Storm passes are historical frequencies for 1991–2020 within 100 nm of one reference point (our choice of radius); they are not a forecast, and a pass within 100 nm does not mean storm-force winds at the anchorage.
- Strong-wind days use NASA POWER's highest hourly mean wind of the day in a ½° × ⅝° grid cell (about 50 km across); real gusts and local winds (funnelling between islands, the bora at the foot of the mountains) are stronger than the cell shows.
- Some grid cells include land (elevation from NASA POWER: 21 m at Ermoupoli, Syros, 138 m at Lefkada), so their winds are lower than at sea.
- Wind direction is the cell's daily mean direction; north-easterly days are our proxy for the bora and northerly days for the meltemi, not observed events.
- Rainfall is NASA POWER's corrected precipitation for the cell, not a rain-gauge normal from the national weather service.
- Official dates ("mid-July", "the cold part of the year") are quoted; our month mapping in the calendar is ours.
Data: JSON.
What we could not verify
- An official Greek page on the meltemi (the Hellenic National Meteorological Service site failed to load for us).
- A start and end date for the meltemi season from an official source.
- We could not open an official Greek page on the meltemi (the Hellenic National Meteorological Service site failed to load for us), so the months come from a peer-reviewed study and the day counts are our calculation.
How to read the labels
- [Peer-reviewed study, not a government source]: a published scientific paper, used where we could open no official page; labelled secondary in our data.
- [Secondary source]: From a newspaper, NGO, guide or tour operator; not official.
- [Not verified]: We could not confirm it. We leave it open rather than guess.
- No label: Read in an official text: government, park authority, ministry or official tourism board.
Counts, shares, means and rainfall totals are our calculation, and say so; radii, thresholds and month mappings are our choices; "our reading" marks an interpretation. None of this is a forecast, a probability or a safety rating.
Sources
- Tyrlis & Lelieveld, Journal of the Atmospheric Sciences: Climatology and dynamics of the summer Etesian winds over the eastern Mediterranean (2013, 70(11): 3374–3396) (peer-reviewed, not official), checked 29 Oct 2026.
- NASA POWER: Prediction Of Worldwide Energy Resources: Daily API (WS10M_MAX, WD10M) and Monthly API (PRECTOTCORR) (official), checked 29 Oct 2026.
- NASA POWER: Prediction Of Worldwide Energy Resources: Monthly API (T2M, WS10M) (official), checked 28 Oct 2026.
- Met Office: Beaufort wind force scale (official), checked 29 Oct 2026.
- UK FCDO (GOV.UK): Greece travel advice: getting help (official), checked 29 Oct 2026.
- European Commission: 112: the European emergency number (official), checked 29 Oct 2026.
- European Commission (Your Europe): Unplanned healthcare: temporary stays (European Health Insurance Card) (official), checked 29 Oct 2026.
Method: methodology. Data: JSON.
More
- Weather risk by month, all destinations
- Best time to charter in Greece, with prices
- Greece: weather by month
- 7-day sailing itinerary in Greece
- 7-day sailing itinerary in Greece: the Cyclades from Lavrio
- Best destinations for families
- Fishing rules in Greece
- Snorkelling and diving in Greece
- Catamaran Index home
Frequently asked questions
When is the meltemi in Greece?
A peer-reviewed study finds that Etesian outbreaks (the meltemi) are "most frequent from mid-July to mid-August" (Tyrlis & Lelieveld, Journal of the Atmospheric Sciences, checked 29 Oct 2026). We could not open an official Greek page on the meltemi, so we give no start or end date for the season.
How strong is the meltemi?
We found no speed for the meltemi in a source we could read, so we give none. On the Met Office scale force 6 (strong breeze) is 22–27 kn (Met Office, checked 29 Oct 2026). At Syros, days reaching 22 kn or more average 4.9 in July and 4.7 in August (our calculation from NASA POWER, 2016–2025; not gusts).
Is the Ionian less windy than the Cyclades?
In our data, yes in July and August: force 6 days average 0.0 and 0.0 at Lefkada against 4.9 and 4.7 at Syros (our calculation, 2016–2025). Lefkada's grid cell includes land (138 m), so it under-reads winds at sea; use it as a comparison, not a forecast.
Can you sail the Cyclades in August?
The study puts the most frequent outbreaks between mid-July and mid-August, and at Syros force 6 days average 4.7 in August (our calculation). Our reading, advice and not a source: plan short legs with sheltered alternatives, consider a skipper if you are unsure, and keep the route flexible. Weather by month: Cyclades itinerary.
Does the meltemi blow in June and September?
The study detects a negative trend in the incidence of outbreaks over June–September, "strikingly strong for September but diminishes in June" (Tyrlis & Lelieveld, Journal of the Atmospheric Sciences, checked 29 Oct 2026). At Syros force 6 days average 1.4 in June and 4.7 in September (our calculation from NASA POWER, 2016–2025).