Popular weather data site Weather Underground (Wunderground) has a new version of its Weather Underground API and two things are notable: its former XML service is being phased out in favor of JSON. And it has a very clear pricing structure, though there's a free version for non-commercial projects.
For as long as people have been grabbing a board and trying to catch some waves, attempting to predict surf quality has been considered an art. Spitcast is trying to turn the art of prediction into the science of surf. Jack Mullis, the founder and developer of Spitcast, has been surfing for years. In 2005 he decided to combine his knowledge of surfing with his degree in Engineering Physics and create a unique algorithm that can predict future surf conditions by using Java and MySQL to cross reference NOAA regional weather data with observations at specific surf spots. This process has been shown to produce predictions accurate to 1 foot standard deviation. With the Spitcast API, this data can be transformed into custom applications.