Weather forecast data from yr.no, delivered by the Norwegian Meteorological Institute and the NRK.
Polman is a service that fetches weather data from yr.no and serves this in a JSON(P) format. It is free and hosted at Heroku on their free trier, try it out here. Note that it is not meant for heavy usage, but perfectly fine for a couple of requests per min.
YR.no offers a great, free to use weather service with weather data from locations all over the world. Please read Information about the free weather data service and Terms of use carefully prior to using this service.
In short, you need to add the text below and also link to the forecast on their site:
Weather forecast from yr.no, delivered by the Norwegian Meteorological Institute and the NRK.
Polman is named after a famous Swedish meteorologist named John Polman.
joel[dot]soderstrom[at]gmail[dot]com