I think it's a little more complex than a song about weather. Mould is using the seasons as a metaphor for the progress of a person's life, specifically the transition from childhood to adolescence (spring to summer right at the beginning of the song), summer being the exciting, tumultuous adolescence - everyone rushing from one carefree and fun activity to the next - finally the song culminating with the end of summer - the end of carefree youth represented by the first snowfall and the transition to the seriousness and somber attitude of adulthood represented by winter (of course winter is emblematic of death which is implied to be the only stage left after the transition to adulthood)
I think it's a little more complex than a song about weather. Mould is using the seasons as a metaphor for the progress of a person's life, specifically the transition from childhood to adolescence (spring to summer right at the beginning of the song), summer being the exciting, tumultuous adolescence - everyone rushing from one carefree and fun activity to the next - finally the song culminating with the end of summer - the end of carefree youth represented by the first snowfall and the transition to the seriousness and somber attitude of adulthood represented by winter (of course winter is emblematic of death which is implied to be the only stage left after the transition to adulthood)
Anyway that's my two cents... could be wrong