WeatherAds is a tool to let you quickly and easily add automated weather based rules to your AdWords, Facebook or Instagram paid advertising campaigns. You cannot use WeatherAds without an active Facebook Ads or Google AdWords account.
Furthermore, in order to use WeatherAds, you will need to have some active campaigns created within AdWords or Facebook, with some budget allocated to them.
WeatherAds is not an ad buying platform, an ad network or an ad exchange. You cannot use WeatherAds to buy ads, only to automate your existing AdWords, Facebook, and Instagram campaigns based on weather.