zyGrib Tutorial – free detailed marine weather

zyGrib Tutorial: what data can you download?

zyGrib is a free software which is just amazing when it comes to marine weather. Please note that while zyGrib continues to work fine, it’s been discontinued and replaced with xyGrib which is a very similar software that is more up to date! It’s available for Windows, Mac, and Linux, and I’ll tell you how to set it up. Below, I offer a quick zyGrib tutorial so you can get started. zyGrib offers the following weather data layers available for free download:

1. Wind speed and direction.
2. Atmospheric pressure (Isobar).
3. Precipitation.
4. Wave height and direction.
5. Surface temperature.
6. Current speed and direction.
7. Total cloud cover.
8. Temperature.
9. Relative Humidity.
10. Snow (No thank you, please).

Here are some example weather data screenshots for southern British Columbia coast that I was able to get in less than 15 seconds using zyGrib. As you can see below, the detail level is truly impressive. It’s incredible what you can have absolutely for free these days. In fact, this is more data than most people would ever need at your fingertips in less than a minute. I am personally blown away. Marine weather can be unpredictable, so there’s good reason to familiarize yourself with the data before heading out. If you need sea surface temperature (SST), take a look here.

Are you looking for a chart plotter system with marine weather? I supply navigation laptops and navigation tablets. Please contact me with any questions!

GRIB files are portable marine weather forecasts

GRIB files are a self contained weather forecast that you can easily download. A GRIB file can include a forecast for one day, or for a longer time period. It can have wave info, or wind info, temperature info, cloud cover, precipitation, and other such weather data. You can download a GRIB file before heading out for the day. Alternatively, you can download it onboard via a cell phone signal, or via a satellite phone (or something like a Garmin inReach) signal even. Once you download the file, you can view it (process is described below) and plan accordingly. Please note that of course the longer the forecast is, the less accurate the data will be. Those supercomputers they use for simulations are powerful, but all models have their limitations. In general, when it comes to weather, sticking to under three days is best.

zyGrib tutorial to download detailed marine weather FOR FREE

Quick note that if you get one of my units, I can do all this for you. I also supply marine charts for your region as well. This can come on a rugged waterproof laptop such as a 10 or 13 inch Toughbook. I have access to high quality GPS antennas, AIS receivers, 12V cigarette plug chargers, and a wide selection of options and upgrades.

1. Download zyGrib for free here. Choose the Windows (most people) or Mac or Linux version as appropriate for your computer.
2. Unzip the files into a folder. Create a shortcut to zyGrib.exe on your desktop if you’d like.
3. Double click on zyGrib.exe to run it.
4. You can use the arrow keys on the keyboard.
5. Left click and drag on the map to select an area.
6. Open file menu (top left) and choose “Download GRIB”. You can also just press CTRL-D. Here you can choose some options:
   • Resolution: how detailed of a forecast you want). I usually leaves this at the highest 0.25 degrees.
   • Interval: time between forecasts, again 3 hours is reasonable.
   • Period: 8 days is just not likely to be that accurate. If you can update more frequently, it would be better. I think 3 days is the practical limit in most cases. This also significantly affects the download size if you’re using zyGrib over a very slow connection like satellite internet at sea.
   • Check all the boxes you want for all the different layers. Uncheck unnecessary things to reduce the download size.
7. The bottom bar will display download size in Kb or Mb. Press download and wait for the server to generate the file.
8. Press “Save”. Note: If you want to use the GRIB file in another software, make a note of the folder you are saving the file to, or save it to a different folder.
9. Voila, you have incredible detailed marine weather data forecast offline on your computer for the area and time period you chose.
10. Use the drop down menu at the top to select the time to see a forecast for that time.
11. Under the “Weather map” menu you can choose which layer you’d like to see.
12. Move the cursor around on the map to see the data for that particular location and time on the left.

zyGrib tutorial (video)

How to overlay marine weather forecast GRIB files with marine charts

All of my navigation laptops and tablets come pre-loaded with software which can overlay marine weather with marine charts (also included with all my systems). This is what it looks like, for example:

It’s actually very simple. Most marine navigation software supports marine weather overlays.

1. You downloaded the GRIB file using zyGrib above and saved it to a location on your computer.
2. zyGrib downloads the GRIB file in a compressed bz2 format to reduce space. Not all software supports this format.
3. If your software supports bz2 files you should be able to just run your navigation program and click and drag the bz2 file you downloaded into it. Otherwise, extract the GRIB file from inside the bz2 file first:
   1. Download and install WinRar. Use the 32 bit version if you’re not sure.
   2. Once you’ve installed it, you should be able to open the bz2 file. Inside it, there will be a .grb file. This is the uncompressed GRIB file your software may need.
   3. Drag the .grb file out of WinRar window into the same folder where the bz2 file by the same name is.
   4. Now you should be able to drag the .grb (uncompressed GRIB file) into your marine navigation software.
4. Refer to the manual of your navigation software to turn on marine weather overlay.