S-41X
Updated on 8 May 2026
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Jump to:Introduction; S-41X PS; Resources; FAQs; Glossary
Introduction
The S-41X series comprises S-100–based Product Specifications for the digital provision of marine weather and sea-ice information to mariners. Developed under the coordination of the World Meteorological Organization (WMO), S-41X products enable graphical marine weather and sea-ice information to be displayed directly in shipborne Electronic Chart Display and Information Systems (ECDIS) as overlays to Electronic Navigational Charts (ENCs).
S-41X supports the global transition to the IHO S-100 Universal Hydrographic Data Model, enhancing route planning, situational awareness, and safety at sea.
S-41X Product Specifications Overview
S-411 and S-412 are part of Roadmap for the S-100 Implementation Decade (2020-2030) Phase 2 Route Planning, with operational readiness targeted from 2029. S-413 and S-414 are planned to follow under Phase 3 of the S-100 Implementation Decade.
| Product Specs. | Scope | Development | Approved | Phase/Planned Operational availability | Lead | Contact |
|---|---|---|---|---|---|---|
| S-411 | Dynamic Ice Information | 1.2.1 | IHO GI registry | 2/2029 | IICWG/ECCC | mmowmo [dot] int (mmo[at]wmo[dot]int) |
| S-412 | Marine Weather Warnings | 1.2.0 | IHO GI registry | 2/2029 | NOAA/OPC | opc [dot] s41xnoaa [dot] gov (opc[dot]s41x[at]noaa[dot]gov) |
| S-413 | Marine Weather Forecast Conditions | / | / | 3/after 2029 | NOAA/OPC | opc [dot] s41xnoaa [dot] gov (opc[dot]s41x[at]noaa[dot]gov) |
| S-414 | Marine Weather Observations | / | / | 3/after 2029 | NOAA/OPC | opc [dot] s41xnoaa [dot] gov (opc[dot]s41x[at]noaa[dot]gov) |
| S-415 | Marine Weather Synoptic Features | / | / | 3/after 2029 | NOAA/OPC | opc [dot] s41xnoaa [dot] gov (opc[dot]s41x[at]noaa[dot]gov) |
It has been identified that there is a need to separate forecast conditions (gridded fields) from synoptic weather features (e.g., fronts and pressure centres), which will result in the definition of two distinct product specifications: S-413 (marine weather forecast conditions) and S-415 (marine weather synoptic features).
Resources
S-41X testing
- IHO GI Registry
- WMO S-41X GitHub repository (for approved PS)
Following endorsement of HSSC17-07.11A, S-41X development documentation and dynamic updates are progressively being made available through the IHO GitHub to facilitate access by industry and technical partners. Stable and approved versions of the specifications are maintained through the WMO GitHub repository.
Members and partner entities are encouraged in testing and providing feedback on the GitHub.
Reports
- WMO update to HSSC16(2024)
- WMO update to HSSC18(2026) [coming]
S-100
FAQs
Governance and Coordination
S-41X development is coordinated within WMO under the Commission for Weather, Climate, Hydrological, Marine and Related Environmental Services and Applications (SERCOM). Strategic oversight and technical coordination are provided by the Standing Committee on Marine Meteorological and Oceanographic Services (SC-MMO) involving various subsidiary bodies, WMO Members and partner entities.
WMO works in close collaboration with:
- The IHO S-100 Working Group (S-100WG)
- The Hydrographic Services and Standards Committee (HSSC)
- National Hydrographic Offices and RENCs
- Industry partners supporting S-100 development and implementation
This coordination ensures alignment with the IMO-IHO S-100 Roadmap, proper registry governance, S-98 (S-100 ECDIS and Interoperability Specification) and consistency across all S-41X specifications.
Timeline
S-41X follows the IHO S-100 Implementation Decade roadmap (2020–2030) and progresses through structured stages:
- Development and publication of Edition 1.0.0 specifications
- Testing and evaluation using test datasets as well as refinement of related specifications document
- Finalization and publication of Edition 2.0.0
- Transition to operational data production
For S-412, Edition 1.0.0 development is expected to be shared for wider review in early 2026, with further validation checks aligned with the development of Edition 2.0.0.
Phase 2 (Target - 2029):
- S-411 - Dynamic Ice Information
- S-412 - Marine Weather Warnings
Phase 3 (Post - 2029)
- S-413 – Marine Weather Forecast Conditions
- S-414 – Marine Weather Observations
- S-415 – Marine Weather Synoptic Features
The relative timelines of Phase 3 specifications remain under development and will be refined as technical work progresses and as implementation priorities become clearer.
The roadmap reflects both technical development and institutional readiness, supporting the gradual global adoption of digital marine weather and ice services.
Implementation Roadmap
The S-41X Implementation Strategy provides guidance to National Meteorological and Hydrological Services (NMHSs), Marine Meteorological Services (MMS), Ice Services, and METAREA Coordinators on transitioning to S-100–based digital products.
The Roadmap focuses on:
- Aligning S-41X products with S-100 standards and ECDIS integration
- Engaging National Hydrographic Offices for technical guidance and collaboration
- Preparing software, validation, and dataset production workflows
- Assessing infrastructure and human resource requirements
- Planning for future broadcasting via evolving maritime connectivity frameworks
The Roadmap also aims to raise awareness among WMO Members regarding the anticipated need for investment in specialised personnel, technical infrastructure, and capacity development.
Implementation requires coordinated investment in technical capacity, data management, and inter-agency collaboration. The phased roadmap allows Members to prepare progressively towards operational readiness, beginning with S-411 and S-412. SC-MMO is developing an implementation Strategy which will be submitted to the SERCOM.
S-41X and MSI
S-41X products are designed to enhance maritime safety by enabling structured, graphical marine weather and sea-ice information to be displayed directly within ECDIS as overlays to Electronic Navigational Charts. While S-411 (Dynamic Ice Information) and S-412 (Marine Weather Warnings) support navigational safety and align with the objectives of the S-100 transition, due to delivery platform performance, they are not currently recognized as official maritime safety information (MSI) under existing IMO frameworks, despite providing the same information. Their status within the MSI regime remains subject to ongoing international discussions as digital S-100 services and delivery methods evolve.
METAREA's role in S-41X
METAREA Coordinators play a central role in the implementation of S-41X by supporting the transition from text-based marine meteorological broadcasts to structured, S-100–compliant digital products. As established authorities for the coordination and dissemination of high seas weather warnings, METAREAs will facilitate the generation, validation, and future transmission of S-411(as appropriate) and S-412 datasets in alignment with evolving maritime communication frameworks. Their collaboration with NMHSs, Ice Services, Hydrographic Offices, and WMO technical bodies is essential to ensure consistency, interoperability, and global coverage during the phased rollout of S-41X services. METAREAs have the responsibilities of supporting coastal states in implementing the S-41X for coastal waters and identifying gaps in coverage.
Glossary
Under development