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Some examples of GRIB viewers to help you choose. It is largely a matter of personal likes and dislikes.

Viewers for GRIB files

WMO (World Meteorological Organisation) developed GRIB code as a means to store and exchange computer output in a compressed form. This was so that the data could then be displayed on any chart whatever the scale or projection.

Third parties providing GRIB data to sailors have developed many viewers. Some are free, some are charged for. Some are intended for use with a particular commercial service. Others will work with GRIB data from any source.

These are a few that I have used. Their principal merits are simplicity and ease of use. I have looked at viewers supplied “free” by various commercial firms but have found some of them over complicated.

Remember that whatever viewer you use, the data all come from NWP (numerical weather prediction) models. For sailing purposes, particularly cruising, my experience of over 50,000 miles sailing is that the US GFS is unlikely to be bettered overall. Using a laptop computer, these viewers, especially the first two will meet your needs. Using a tablet or smartphone, the range is wider. See my GRIB apps page.

GRIB files usually have the extension .grb, Some are compressed further and have extensions .grb.bz2.




The first GRIB viewer developed by SailDocs for users of SailMail, the user funded HF radio service. There have been few changes; it is basic, easy to use with crude topography and no frills. For details, send a blank email to info@saildocs.com.



My preferred viewer. There are PC, MacOS and Linux versions Many data options. Choose the presentation, colours etc to meet your personal likes Intended for use with the totally free zyGrib but it will read both .grb and .grb.bz2 from other sources. It is a good viewer for displaying high resolution data.

Software from the zyGrib site in a compressed form or as a rather large download from the Dutch magazine Zilt.



An easy to use viewer from Theyr.com for PC, Mac OS and Linux. Only works with .grb and NOT ,grb,bz2.



The MaxSea viewer is another simple viewer with few frills. There can be problems in getting a key. Start from Zilt, the Dutch Online Magazine Site and be careful to follow the instructions in their guide.



This is the viewer developed by Predictwind for their offshore app. This is provided free to advertise their wide-ranging weather and weather routing apps. It can be used to view GRIB data from other sources such as the Meteoconsut high resolution forecasts.

Other viewers are available to buy but I see no reason to do so. Most viewers have the facility to let you read the actual forecast speed. That helps distinguish between a 15 knot wind vector which could be anything between 12.5 and 17.5 knots. They can usually display weather at a point as a time sequence. Most will let you step on one chart at a time or give you a movie.

Various chart-plotters have their tailor-made versions which will be similar to those that I have listed above.

The next is not a GRIB viewer in that it is not a standalone piece of software for viewing NWP output. However, it is sufficiently different to be worth showing here.



Meteociel is one of the most comprehensive ways of seeing forecasts from many sources worldwide. Some of the wind charts are in conventional vector format but many are in stream-line form as shown here. These will not be to everyone’s taste but they do show well the variability that exists in the weather.

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