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.
Onset, a supplier of data logging devices, just launched the HOBOlink® Web Services API, that enables anyone to easily build applications around weather, energy and environmental data gathered from the Onset HOBO® U30 monitoring systems, hardware you install in your environment which can share its status up to Onset's system.
Last month, ProgrammableWeb reported that Metwit was releasing a free, short term trial plan of the Metwit Weather API to help developers who have created applications using Yahoo! Weather APIs and have been impacted by the shut down of the Yahoo! Geocoding API. Metwit has now announced the addition of a brand new feature to the Metwit Weather API: Push Weather Notifications.