The Chart gets format and data via the Ajax call. It uses a jquery plug in that charts data called highcharts. Highcharts was used because it has a large variety of features and it falls back gracefully on older browsers. The chart is designed to be viewed on tablets and phones but also works on desktops.
Data is gathered from the weatherunderground.com site using an api key. Its gathered and stored in a local mysql table. The hourly data is then sumarized and stored for less fine grained queries.