This graph was generated based on METAR data from the NOAA Aviation Weather website. Have a look at the source.
This is real data generated on the fly when you load this page based on available METAR information.
The graph shows wind speeds over time with the latest to the right and the oldest data to the left. The data is obtained from the Aviation Weather website under the following link: http://aviationweather.gov/adds/metars
The graph shows the maximum of available 99 hours of data from the Aviation Weather side. This corresponds roughly to 4 days of history. The blue line shows normal wind speeds in knots. When gust is reported the gusts are shown as red area. Hover your mouse over the graph to see specific data points. It will show you time, wind speed in knots and gusts in knots if applicable. The time shows the day of the month in the first two numbers, the rest shows time in 2400 hour format, always UTC.
To change the airport, type the 4 letter ICAO code into the text box above the graph and click the Generate Graph button. If the graph is empty or shows an error, the ICAO code most likely wasnt found in the Aviation Weather website or the format of the METAR reports differs from the standard. Go to http://aviationweather.gov/adds/metars and type the same ICAO code if you have problems. If you dont see any valid data, the graph cannot be generated.
PHP queries the Aviation Website for the METAR data and generates a Java Script Array from the results. Google Charts is used for the graph and it consumes the array that was created by PHP.