The user assumes the entire risk related to its use of this weather data. PassageWeather.com is providing this data "as is", and PassageWeather.com disclaims any and all warranties, whether express or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose. In no event will PassageWeather.com be liable to you or to any third party for any direct, indirect, incidental, consequential, special or exemplary damages or lost profit resulting from any use or misuse of this data.

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About our Weather Data

These forecasts are produced from computer models and may not always reflect official forecasts, especially in the vicinity of weather fronts, tropical cyclones (tropical depressions, tropical storms, hurricanes, typhoons, etc.) or in rapidly changing conditions. As they contain no input from weather forecasters, it is important to check the official marine forecasts and warnings for your area when strong winds or tropical cyclones are forecast.

GRIB data is extracted from a computer forecast model. While such computer data can provide useful guidance for general wind flow, there are limitations which must be understood. What you are receiving is a weather prediction generated by a computer run by NOAA/NCEP (GFS, WW3, NAM and RTOFS models), the US Navy (COAMPS) or the Cyprus Oceanography Center (WAM4-MED) and downloaded and processed by PassageWeather.com. The network is complex, and any computer network is subject to hardware and software failures or human error which can effect accuracy or availability of data. In particular, if our servers were not able to download a current data file then the forecast may be based on old data.

Also remember that GRIB data is not reviewed by forecasters before being made available. You are getting a small part of the raw model data that the forecasters themselves use when writing a forecast, and it is your responsibility to make sure that the data is consistent with your local conditions and with the professionally-generated forecasts (e.g. text bulletins and weather-fax charts).

GRIB data also has limitations along shore, where local effects often dominate and may not be adequately modeled. In addition these models cannot provide adequate prediction for tropical systems, frontal activity or convergence zones. For example, while global models can provide useful data on the likely track of hurricanes, they grossly underestimate the strength of hurricanes because of their small size compared to the model grid. For hurricane/cyclone forecasts, carefully monitor the appropriate warning messages and do not rely on GRIB data as your only source of weather information.

That all said, GRIB data can provide useful guidance not available elsewhere. Understand the limitations and use the data carefully. GRIB data should be considered supplemental to other forecasts, and not be relied upon in lieu of professionally-generated charts or forecasts.