You can enter an encoded METAR into the top text area. Click "Decode" to have the weather report translated into a human-readable format.
Please note that METARs which are in the standard US format are not supported.
The decoder doesn't convert all weather situations you will find in a METAR, but all basic weather parameters will be decoded.
You can also use the example buttons 1-4 to see examples of how the decoder works.
This tool will help you to understand the basic format of a METAR, however it:
If you see something in a METAR which you do not understand, you should consult a key of METAR parameters, or ask someone who will know.
Wikipedia provides basic information on METAR parameters which you can use.