Two years ago, I wrote a software package for R called “rNOMADS” that interfaces with online weather and sea ice model repositories to gather data in real time, for free. The data are delivered in two ways: a simple, pure R, cross platform interface using GrADS-DODS, and binary files in GRIB format. The one issue with GRIB is that this format can’t be read directly into R; it requires the external program “wgrib2.” Installing rNOMADS with GRIB support for Linux is covered in this post (Mac OS is probably similar). I thought GRIB support for Windows was impossible until the guy who runs this blog casually told me he’d figured it out. So, I finally got around to trying it myself, and I’m happy to say I got it to work! Here’s how:
Download the most recent wgrib2.exe version and all DLL files from Wesley Ebisuzaki’s web site: Click here.
Make a directory somewhere on your computer. I chose: C:\Program Files\wgrib2
Copy the .exe and the .dll files to this directory.
Append the directory path to the Windows PATH variable. Find out how to do this here.
Edit: a user points out that sometimes this doesn’t work. If not, change the path variable in R using Sys.setenv():
Sys.setenv("PATH" = "C:/Program Files/wgrib2")
Step 4: If R is open, close and reopen it. Then try the following command in the R interpreter:
If you get a bunch of text that looks like the image below, you’ve succeeded. You can start reading GRIB files with rNOMADS!