Tomakomai Ko (JPTMK) — marine weather & port guide
Tomakomai Ko is a port in Japan at 42°38.0′N 141°38.0′E. Today (Aug 3): SSW wind 5–7 kn, waves 2.1–2.6 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 | 42°38.0′N 141°38.0′E |
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| UN/LOCODE | JPTMK |
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| Harbor size | Small |
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| Harbor type | Coastal breakwater harbor |
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| Shelter | Excellent |
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| Channel depth | 14 m |
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| Anchorage depth | 14 m |
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| Tide range | 2 m |
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| Pilotage | Advisable |
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| Time zone | Asia/Tokyo |
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10-day marine forecast — Tomakomai Ko
| Date | Wind | Gusts | Waves |
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| SSW 5–7 kn | 20 kn | 2.1–2.6 m |
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| SSW 7–9 kn | 25 kn | 2.6–2.9 m |
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| SSW 6–8 kn | 23 kn | 2.2–2.8 m |
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| SSW 4–7 kn | 20 kn | 1.7–2.1 m |
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| SSW 7–9 kn | 19 kn | 1.5–1.7 m |
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| NE 4–8 kn | 10 kn | 1.5–1.6 m |
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| NNE 4–5 kn | 6 kn | 2.2–2.2 m |
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| N 6–6 kn | 16 kn | 2.8–2.8 m |
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| N 9–9 kn | 42 kn | 2.8–2.8 m |
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| SSW 7–7 kn | 24 kn | 1.5–1.5 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 Tomakomai Ko right now?
As of the ECMWF IFS run 2026-08-03 12z: SSW wind 5–7 kn, waves 2.1–2.6 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 Tomakomai Ko?
Tomakomai Ko is classed as a small harbor (coastal breakwater harbor), with excellent shelter in the NGA World Port Index.
How deep is the approach to Tomakomai Ko?
Per the NGA World Port Index, the entrance channel carries about 14 m and anchorage depths run about 14 m. Verify against current official charts before entry.
What restricts entry to Tomakomai Ko?
Entry is affected by heavy swell, overhead clearance limits. Check the live forecast on this page and official notices before approach.