AIS Fleet's weather forecasts, tide predictions and weather observations are built from the sources below, each credited here in the form its licence asks for, where it asks for one. Every response that carries their data links this page, and its credits give the credit its sources' licences ask for.

Weather forecasts

ECMWF. This service is based on data and products of the European Centre for Medium-Range Weather Forecasts (ECMWF). Source: www.ecmwf.int. This ECMWF data is published under a Creative Commons Attribution 4.0 International (CC BY 4.0) licence, creativecommons.org/licenses/by/4.0. ECMWF does not accept any liability whatsoever for any error or omission in the data, their availability, or for any loss or damage arising from their use.

Modified: AIS Fleet reads ECMWF's 0.1 degree open-data forecast (waves at 0.25 degree) at the grid point nearest the requested place, or for ocean currents and waves near a coast at the nearest point at sea, and converts it into wind and current speeds and directions and rain per forecast step, in the units each response states.

Tide predictions

• NOAA Center for Operational Oceanographic Products and Services (CO-OPS). Tide and tidal current predictions at United States stations are computed from the harmonic constants NOAA publishes, which are in the public domain.
• Danish Meteorological Institute (DMI), www.dmi.dk, licensed under CC BY 4.0. Tide predictions at stations in Denmark, the Faroe Islands and Greenland are computed from harmonic constants that the Slackwater tide station database derives from DMI's own predictions. Modified: AIS Fleet computes predictions using the conventions used to derive these constants.
• Toitū Te Whenua Land Information New Zealand. This work is based on Toitū Te Whenua Land Information New Zealand data which are licensed by Toitū Te Whenua Land Information New Zealand for re-use under the Creative Commons Attribution 4.0 International licence. Tide predictions at New Zealand stations are computed from its harmonic constants.
• © Kartverket / Norwegian Mapping Authority, Hydrographic Service, www.kartverket.no, licensed under CC BY 4.0. Tide predictions at Norwegian stations are computed from its harmonic constants.
• Source: Japan Coast Guard, Hydrographic and Oceanographic Department, www1.kaiho.mlit.go.jp, under the Government of Japan Standard Terms of Use (Version 2.0) (terms). Edited by Open Waters: constituent names, units and phases converted; tidal datums derived. Open Waters publishes the Slackwater tide station database. Tide predictions at Japanese stations are computed by AIS Fleet from the edited harmonic constants.
• TICON-4. Hart-Davis, M., Dettmering, D., Seitz, F. (2025), TICON-4: TIdal CONstants based on GESLA-4 sea-level records, SEANOE, doi.org/10.17882/109129, licensed under CC BY 4.0. Tide predictions at stations around the world are computed from its harmonic constants, including constants that the Slackwater database recalculates to correct observation times. Modified: predictions follow the conventions used to derive each station's constants, with phase conversions where needed.
• The Slackwater tide station database, github.com/openwatersio/slackwater-database, licensed under CC BY 4.0. It compiles the tide stations used here, with their constants and datums. Modified: predictions are computed from it.
• FES2022. The FES2022 Tide product was funded by CNES, produced by LEGOS, NOVELTIS and CLS and made freely available by AVISO (DOI 10.24400/527896/a01-2024.004, licence). It is used where no usable tide station is nearby. Modified: its constants stored to the millimetre for each grid cell, and the lowest and highest astronomical tides and the predictions computed from them.

Stations with a known location error are excluded until corrected. Predictions then come from another usable nearby station or, where available, the global model.

A tide prediction covers only the astronomical tide. It leaves out storm surge, pressure, wind and river flow.

Retrying a paid tide request returns its original predictions and source credits during the payment recovery window, even if the station data has since changed. A new purchase uses the data available at that time.

Weather observations

• NOAA Aviation Weather Center. Airport weather reports (METAR), in the public domain for US stations. Reports from other countries reach it through the World Meteorological Organization's international exchange.
• NOAA National Data Buoy Center. Buoy and coastal station readings, in the public domain unless NDBC notes otherwise for a partner's station.
• Source: Deutscher Wetterdienst. Synoptic weather station reports, licensed under CC BY 4.0. Modified: wind read from each report and converted to knots.
• AIS Fleet. Wind readings from Saillogger boats whose owners publish their weather to Windy, without their names or MMSIs and with positions rounded to a hundredth of a degree.

None of this data is for navigation. For passage planning and safety, use official forecasts and tide tables.