{ "destination": "greece", "name": "Greece", "hazard": "meltemi", "has_page": true, "question": "When is the meltemi in Greece?", "answer": "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.", "answer_markdown": "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": "2026-10-29", "canonical_url": "https://catamaranindex.com/weather-risk/greece/", "api_url": "https://catamaranindex.com/api/weather-risk/greece.json", "best_time_url": "https://catamaranindex.com/best-time/greece/", "book_url": "https://catamaranindex.com/go/samboat?dest=greece&pos=api", "calendar": [ { "month": 1, "name": "January", "codes": [], "notes": [] }, { "month": 2, "name": "February", "codes": [], "notes": [] }, { "month": 3, "name": "March", "codes": [], "notes": [] }, { "month": 4, "name": "April", "codes": [], "notes": [] }, { "month": 5, "name": "May", "codes": [], "notes": [] }, { "month": 6, "name": "June", "codes": [], "notes": [] }, { "month": 7, "name": "July", "codes": [ "meltemi-peak" ], "notes": [ "from mid-July" ] }, { "month": 8, "name": "August", "codes": [ "meltemi-peak" ], "notes": [ "to mid-August" ] }, { "month": 9, "name": "September", "codes": [], "notes": [] }, { "month": 10, "name": "October", "codes": [], "notes": [] }, { "month": 11, "name": "November", "codes": [], "notes": [] }, { "month": 12, "name": "December", "codes": [], "notes": [] } ], "storms": null, "wind": [ { "point": "greece-cyclades", "place": "Ermoupoli, Syros", "lat": 37.445, "lon": 24.94, "elev_m": 20.74, "years": 10, "months": [ { "month": 1, "name": "January", "force5_days": 17.8, "force6_days": 9.6, "force6_days_total": 96, "force6_direction_counts_45deg_from_0": [ 44, 0, 0, 5, 21, 11, 3, 12 ], "force6_share_north_east": 0.4583333333333333, "force6_share_south_east": 0.052083333333333336, "force6_share_northerly": 0.5833333333333334, "mean_wind_kn": 14, "rain_mm": 115 }, { "month": 2, "name": "February", "force5_days": 14.6, "force6_days": 9.3, "force6_days_total": 93, "force6_direction_counts_45deg_from_0": [ 59, 0, 2, 7, 12, 7, 0, 6 ], "force6_share_north_east": 0.6344086021505376, "force6_share_south_east": 0.0967741935483871, "force6_share_northerly": 0.6989247311827957, "mean_wind_kn": 13.6, "rain_mm": 68 }, { "month": 3, "name": "March", "force5_days": 15.2, "force6_days": 7.4, "force6_days_total": 74, "force6_direction_counts_45deg_from_0": [ 45, 1, 0, 4, 4, 10, 2, 8 ], "force6_share_north_east": 0.6216216216216216, "force6_share_south_east": 0.05405405405405406, "force6_share_northerly": 0.7162162162162162, "mean_wind_kn": 12.6, "rain_mm": 49 }, { "month": 4, "name": "April", "force5_days": 9.7, "force6_days": 3.7, "force6_days_total": 37, "force6_direction_counts_45deg_from_0": [ 23, 1, 2, 4, 1, 0, 1, 5 ], "force6_share_north_east": 0.6486486486486487, "force6_share_south_east": 0.16216216216216217, "force6_share_northerly": 0.7567567567567568, "mean_wind_kn": 10.4, "rain_mm": 27 }, { "month": 5, "name": "May", "force5_days": 6.4, "force6_days": 1.9, "force6_days_total": 19, "force6_direction_counts_45deg_from_0": [ 12, 0, 0, 2, 0, 1, 0, 4 ], "force6_share_north_east": 0.631578947368421, "force6_share_south_east": 0.10526315789473684, "force6_share_northerly": 0.8421052631578947, "mean_wind_kn": 9.3, "rain_mm": 21 }, { "month": 6, "name": "June", "force5_days": 6.7, "force6_days": 1.4, "force6_days_total": 14, "force6_direction_counts_45deg_from_0": [ 9, 0, 0, 1, 0, 0, 0, 4 ], "force6_share_north_east": 0.6428571428571429, "force6_share_south_east": 0.07142857142857142, "force6_share_northerly": 0.9285714285714286, "mean_wind_kn": 9.9, "rain_mm": 15 }, { "month": 7, "name": "July", "force5_days": 14.3, "force6_days": 4.9, "force6_days_total": 49, "force6_direction_counts_45deg_from_0": [ 29, 0, 0, 0, 0, 0, 0, 20 ], "force6_share_north_east": 0.5918367346938775, "force6_share_south_east": 0, "force6_share_northerly": 1, "mean_wind_kn": 13.1, "rain_mm": 5 }, { "month": 8, "name": "August", "force5_days": 15.4, "force6_days": 4.7, "force6_days_total": 47, "force6_direction_counts_45deg_from_0": [ 29, 0, 0, 0, 0, 0, 0, 18 ], "force6_share_north_east": 0.6170212765957447, "force6_share_south_east": 0, "force6_share_northerly": 1, "mean_wind_kn": 13.4, "rain_mm": 6 }, { "month": 9, "name": "September", "force5_days": 12.1, "force6_days": 4.7, "force6_days_total": 47, "force6_direction_counts_45deg_from_0": [ 42, 0, 0, 0, 0, 0, 1, 4 ], "force6_share_north_east": 0.8936170212765957, "force6_share_south_east": 0, "force6_share_northerly": 0.9787234042553191, "mean_wind_kn": 12.5, "rain_mm": 17 }, { "month": 10, "name": "October", "force5_days": 11.9, "force6_days": 3.9, "force6_days_total": 39, "force6_direction_counts_45deg_from_0": [ 37, 0, 0, 1, 0, 0, 0, 1 ], "force6_share_north_east": 0.9487179487179487, "force6_share_south_east": 0.02564102564102564, "force6_share_northerly": 0.9743589743589743, "mean_wind_kn": 12, "rain_mm": 47 }, { "month": 11, "name": "November", "force5_days": 12.7, "force6_days": 4.6, "force6_days_total": 46, "force6_direction_counts_45deg_from_0": [ 27, 0, 0, 2, 11, 1, 4, 1 ], "force6_share_north_east": 0.5869565217391305, "force6_share_south_east": 0.043478260869565216, "force6_share_northerly": 0.6086956521739131, "mean_wind_kn": 12.4, "rain_mm": 72 }, { "month": 12, "name": "December", "force5_days": 14.7, "force6_days": 6.9, "force6_days_total": 69, "force6_direction_counts_45deg_from_0": [ 45, 1, 0, 2, 13, 4, 0, 4 ], "force6_share_north_east": 0.6666666666666666, "force6_share_south_east": 0.028985507246376812, "force6_share_northerly": 0.7101449275362319, "mean_wind_kn": 13.2, "rain_mm": 104 } ] }, { "point": "greece", "place": "Lefkada", "lat": 38.833, "lon": 20.707, "elev_m": 138.13, "years": 10, "months": [ { "month": 1, "name": "January", "force5_days": 4.2, "force6_days": 0.7, "force6_days_total": 7, "force6_direction_counts_45deg_from_0": [ 0, 2, 0, 1, 1, 2, 0, 1 ], "force6_share_north_east": 0.2857142857142857, "force6_share_south_east": 0.14285714285714285, "force6_share_northerly": 0.14285714285714285, "mean_wind_kn": 8.1, "rain_mm": 145 }, { "month": 2, "name": "February", "force5_days": 3.6, "force6_days": 0.3, "force6_days_total": 3, "force6_direction_counts_45deg_from_0": [ 0, 2, 0, 1, 0, 0, 0, 0 ], "force6_share_north_east": 0.6666666666666666, "force6_share_south_east": 0.3333333333333333, "force6_share_northerly": 0, "mean_wind_kn": 7.9, "rain_mm": 90 }, { "month": 3, "name": "March", "force5_days": 2.7, "force6_days": 0.6, "force6_days_total": 6, "force6_direction_counts_45deg_from_0": [ 0, 0, 2, 2, 0, 0, 2, 0 ], "force6_share_north_east": 0, "force6_share_south_east": 0.6666666666666666, "force6_share_northerly": 0, "mean_wind_kn": 7.2, "rain_mm": 97 }, { "month": 4, "name": "April", "force5_days": 1, "force6_days": 0.2, "force6_days_total": 2, "force6_direction_counts_45deg_from_0": [ 0, 0, 1, 0, 0, 1, 0, 0 ], "force6_share_north_east": 0, "force6_share_south_east": 0.5, "force6_share_northerly": 0, "mean_wind_kn": 6.5, "rain_mm": 42 }, { "month": 5, "name": "May", "force5_days": 0.7, "force6_days": 0, "force6_days_total": 0, "force6_direction_counts_45deg_from_0": [ 0, 0, 0, 0, 0, 0, 0, 0 ], "force6_share_north_east": null, "force6_share_south_east": null, "force6_share_northerly": null, "mean_wind_kn": 5.9, "rain_mm": 48 }, { "month": 6, "name": "June", "force5_days": 0.5, "force6_days": 0, "force6_days_total": 0, "force6_direction_counts_45deg_from_0": [ 0, 0, 0, 0, 0, 0, 0, 0 ], "force6_share_north_east": null, "force6_share_south_east": null, "force6_share_northerly": null, "mean_wind_kn": 5.5, "rain_mm": 37 }, { "month": 7, "name": "July", "force5_days": 0.5, "force6_days": 0, "force6_days_total": 0, "force6_direction_counts_45deg_from_0": [ 0, 0, 0, 0, 0, 0, 0, 0 ], "force6_share_north_east": null, "force6_share_south_east": null, "force6_share_northerly": null, "mean_wind_kn": 6, "rain_mm": 16 }, { "month": 8, "name": "August", "force5_days": 0.1, "force6_days": 0, "force6_days_total": 0, "force6_direction_counts_45deg_from_0": [ 0, 0, 0, 0, 0, 0, 0, 0 ], "force6_share_north_east": null, "force6_share_south_east": null, "force6_share_northerly": null, "mean_wind_kn": 5.5, "rain_mm": 32 }, { "month": 9, "name": "September", "force5_days": 1.1, "force6_days": 0, "force6_days_total": 0, "force6_direction_counts_45deg_from_0": [ 0, 0, 0, 0, 0, 0, 0, 0 ], "force6_share_north_east": null, "force6_share_south_east": null, "force6_share_northerly": null, "mean_wind_kn": 6.1, "rain_mm": 80 }, { "month": 10, "name": "October", "force5_days": 0.9, "force6_days": 0.1, "force6_days_total": 1, "force6_direction_counts_45deg_from_0": [ 0, 0, 0, 1, 0, 0, 0, 0 ], "force6_share_north_east": 0, "force6_share_south_east": 1, "force6_share_northerly": 0, "mean_wind_kn": 6.4, "rain_mm": 100 }, { "month": 11, "name": "November", "force5_days": 3.6, "force6_days": 0.8, "force6_days_total": 8, "force6_direction_counts_45deg_from_0": [ 0, 0, 2, 2, 0, 2, 1, 1 ], "force6_share_north_east": 0, "force6_share_south_east": 0.5, "force6_share_northerly": 0.125, "mean_wind_kn": 8.1, "rain_mm": 190 }, { "month": 12, "name": "December", "force5_days": 3.1, "force6_days": 0.2, "force6_days_total": 2, "force6_direction_counts_45deg_from_0": [ 0, 0, 0, 1, 1, 0, 0, 0 ], "force6_share_north_east": 0, "force6_share_south_east": 0.5, "force6_share_northerly": 0, "mean_wind_kn": 7.5, "rain_mm": 143 } ] } ], "season": [ { "text": "\"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).", "status": "secondary", "sources": [ { "id": "wr_etesians_tyrlis2013", "name": "Tyrlis & Lelieveld, Journal of the Atmospheric Sciences", "title": "Climatology and dynamics of the summer Etesian winds over the eastern Mediterranean (2013, 70(11): 3374–3396)", "url": "https://doi.org/10.1175/JAS-D-13-035.1", "checked": "2026-10-29", "note": "Peer-reviewed study, not a government source. Abstract read via Crossref; ERA-40 reanalysis.", "tier": "reference" } ] }, { "text": "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).", "status": "secondary", "sources": [ { "id": "wr_etesians_tyrlis2013", "name": "Tyrlis & Lelieveld, Journal of the Atmospheric Sciences", "title": "Climatology and dynamics of the summer Etesian winds over the eastern Mediterranean (2013, 70(11): 3374–3396)", "url": "https://doi.org/10.1175/JAS-D-13-035.1", "checked": "2026-10-29", "note": "Peer-reviewed study, not a government source. Abstract read via Crossref; ERA-40 reanalysis.", "tier": "reference" } ] } ], "context": [], "method": { "storms": "Storm passes: from NOAA's HURDAT2 best-track file (hurdat2-1851-2025-092326.txt) we take every tropical storm or hurricane (HURDAT2 status TS or HU) whose track starts in 1991–2020, NHC's 30-year climate period. We interpolate the track in a straight line every 60 minutes between fixes (not across gaps over 12 hours) and count a storm once, in the month it first came within 100 nm of our reference point. The 100 nm radius, the interpolation and the month rule are our choices. \"Storm-years\" are the years out of 30 with at least one pass in that month. Our calculation.", "wind": "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": "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": "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." }, "caveats": [ "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." ], "derived": "Storm passes, shares, strong-wind days, direction shares and rainfall are our calculation from NOAA HURDAT2 and NASA POWER.", "insurance_note": "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.", "not_verified": [ "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." ], "status_legend": { "official": "Read in an official text: government, park authority, ministry or official tourism board.", "secondary": "From a newspaper, NGO, guide or tour operator; not official.", "not_verified": "We could not confirm it. We leave it open rather than guess." }, "sources": [ { "id": "wr_etesians_tyrlis2013", "name": "Tyrlis & Lelieveld, Journal of the Atmospheric Sciences", "title": "Climatology and dynamics of the summer Etesian winds over the eastern Mediterranean (2013, 70(11): 3374–3396)", "url": "https://doi.org/10.1175/JAS-D-13-035.1", "checked": "2026-10-29", "note": "Peer-reviewed study, not a government source. Abstract read via Crossref; ERA-40 reanalysis.", "tier": "reference" }, { "id": "wr_nasa_power_daily", "name": "NASA POWER", "title": "Prediction Of Worldwide Energy Resources: Daily API (WS10M_MAX, WD10M) and Monthly API (PRECTOTCORR)", "url": "https://power.larc.nasa.gov/docs/services/api/temporal/daily/", "checked": "2026-10-29", "note": "Pulled with scripts/fetch-weather-daily.mjs for 2016–2025 at our 10 reference points and 2 route points. WS10M_MAX is the highest hourly mean of the day in a ½° × ⅝° grid cell, not a gust. Strong-wind day counts and rainfall means are our calculation.", "tier": "official" }, { "id": "su_metoffice_beaufort", "name": "Met Office", "title": "Beaufort wind force scale", "url": "https://weather.metoffice.gov.uk/guides/coast-and-sea/beaufort-scale", "checked": "2026-10-29", "note": "UK national weather service. No page date. Force 2 (light breeze) 4–6 kn; force 4 (moderate breeze) 11–16 kn. We use 6 and 16 kn as the anchors of our wind score. Force 5 (fresh breeze) 17–21 kn; force 6 (strong breeze) 22–27 kn. We use 17 and 22 kn as the thresholds of our strong-wind day counts.", "tier": "official" }, { "id": "nasa_power_monthly", "name": "NASA POWER", "title": "Prediction Of Worldwide Energy Resources: Monthly API (T2M, WS10M)", "url": "https://power.larc.nasa.gov/docs/services/api/temporal/monthly/", "checked": "2026-10-28", "note": "Monthly point data for 2016–2025 pulled on 28 Oct 2026 with scripts/fetch-weather.mjs (API v2.10.0, community RE, parameters T2M = temperature at 2 m in °C and WS10M = wind speed at 10 m in m/s; meteorological grid ½° × ⅝° per https://power.larc.nasa.gov/docs/methodology/). One request per reference point, in the form https://power.larc.nasa.gov/api/temporal/monthly/point?parameters=T2M,WS10M&community=RE&longitude=&latitude=&start=2016&end=2025&format=JSON (coordinates in src/data/weather.ts). Route points for the Dubrovnik and Cyclades itineraries are in src/data/weather-routes.ts (scripts/fetch-route-weather.mjs, pulled 29 Oct 2026). Credit: https://power.larc.nasa.gov/docs/referencing/ . The pages we opened did not state a licence; NASA data is described to us as free for any use. Palma (Mallorca) reference point for the Mallorca vs Ibiza comparison in src/data/weather-routes.ts (scripts/fetch-route-weather.mjs, pulled 29 Oct 2026)." } ], "attribution": "Cite \"Catamaran Index\" with a link to the canonical_url of the page the figure comes from, and name the original source listed with it.", "affiliate_note": "book_url links go through /go/samboat, an affiliate link: Catamaran Index may earn a commission on bookings, at no extra cost to the traveller. It never changes the data." }