In the South Hemisphere, the seasons are opposed as those in the North Hemisphere. So, March is the last month of summer, and usually there is a lot of rain. The title "Waters of March" refers to that rainy period. Digging deeper a little bit, those last rains of summer could also be interpreted like the completion of cleaning mind and spirit of a person, getting him (or her) ready and open for new experiences. Jobim certainly embraces this viewpoint, as in the last verses of the Portuguese lyrics:
"São as águas de março fechando o verão
São promessas de vida no meu coração"
("While the rains of March close the summer period
I can feel new signs of life in my heart").
The context of the Portuguese lyrics is much more important than that of the English lyrics. As a matter of fact, it would be much more profitable to go into the meaning of the Portuguese lyrics.
Jobim had to allow himself to make a few essencial modifications when writing the English lyrics. For instance, in Brasil, the end of March is also the end of the last rains of the summer period. He decided to follow a different path in the English verses, so that it would result more familiar to people living in the North Hemisphere.
He wrote the song in his family real estate property, in the interior of Rio de Janeiro State. It was raining all over, and the roads were full of mud. Furthermore, he was building a new wall along the limits of the property, and the whole scene was a big mess. All these impressions were brought into the Portuguese lyrics. He talks about many tipical things of the day-to-day life of those who live in Rio de Janeiro's inland.
