Who says nobody does anything about the weather? Danny Dunn does! Of course if there hadn''t been a drought when Danny went to the weather bureau to return a radiosonde, just maybe nothing would have happened. But has there ever been a time when Danny could contain his curiosity? Danny is naturally attracted to all the weather-forecasting instruments and decides to do some volunteer weather-observing. And when Danny and his friends Joe Pearson and Irene Miller discover that Professor Bullfinch has a new ionic transmitter that makes little clouds and miniature rainstorms, trouble is sure to follow!