This project is really just a personal exercise in the use of JavaFX and the WidgetFX SDK.
Both platforms are relatively new and will (hopefully) continue to evolve.
The primary source of weather data for this widget is the Yahoo weather API.
Unfortunately, Yahoo provides limited forecast data (today and tomorrow only) - so there is an option to also query a weather API hosted by Google for a 4 day forecast.
Other options / features include:
build a list of favorite locations - top item in list is the default location at start-up
cycle through favorite locations by clicking on location name
toggle units (celcius/farenheight) by clicking on current temperature
change skin (appearance) by clicking on the icon displayed for current condition
expand a forecast by clicking on it (makes it easier to read when widget is minimized)
extended weather information (maps, detailed forecasts) can be obtained by clicking on the icons denoting Yahoo and/or Google
This weather widget queries for updates in weather data every 20 minutes (forecasts are typically updated at source every hour or so).
Note: WidgetFX requires Java SE 6 or higher. For best results Install Java 6 prior to running.