Isla San Marcos (MXSMI) — marine weather & port guide
Isla San Marcos is a port in Mexico at 27°13.0′N 112°6.0′W. Today (Aug 3): NNE wind 4–8 kn, waves 0.3–0.4 m, from the ECMWF IFS run 2026-08-03 12z. The live chart on this page shows current conditions and plans weather-optimized departures from this harbor.
Port facts (NGA World Port Index)| Position | 27°13.0′N 112°6.0′W |
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| UN/LOCODE | MXSMI |
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| Harbor size | Very small |
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| Harbor type | Open roadstead |
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| Shelter | Poor |
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| Anchorage depth | 17 m |
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| Tide range | 0 m |
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| Pilotage | Compulsory |
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| Time zone | America/Mazatlan |
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10-day marine forecast — Isla San Marcos
| Date | Wind | Gusts | Waves |
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| NNE 4–8 kn | 10 kn | 0.3–0.4 m |
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| SSE 4–10 kn | 14 kn | 0.5–0.8 m |
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| SSE 4–13 kn | 17 kn | 0.5–0.9 m |
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| SSE 6–13 kn | 18 kn | 0.3–0.7 m |
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| S 5–9 kn | 13 kn | 0.3–0.3 m |
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| WNW 2–11 kn | 14 kn | 0.2–0.5 m |
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| SSE 3–12 kn | 15 kn | 0.6–0.6 m |
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| WSW 4–4 kn | 11 kn | 0.6–0.6 m |
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| SW 7–7 kn | 10 kn | 0.5–0.5 m |
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| SW 5–5 kn | 9 kn | 0.4–0.4 m |
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Forecast from the ECMWF IFS model run , waves from ECMWF WAM. Updated with each model cycle; the live chart below recalculates for your departure time and vessel.
Frequently asked
How is the weather at Isla San Marcos right now?
As of the ECMWF IFS run 2026-08-03 12z: NNE wind 4–8 kn, waves 0.3–0.4 m. The 10-day outlook is in the forecast table on this page and updates with each model cycle.
How big is the harbor at Isla San Marcos?
Isla San Marcos is classed as a very small harbor (open roadstead), with poor shelter in the NGA World Port Index.
How deep is the approach to Isla San Marcos?
Per the NGA World Port Index, anchorage depths run about 17 m. Verify against current official charts before entry.
What restricts entry to Isla San Marcos?
Entry is affected by tidal windows, heavy swell. Check the live forecast on this page and official notices before approach.