ORDER the result of a query by date

Hello;
I've got the result of a query that appears as:cod_variable | cod_station | year | month | day | rain
---------------------+-------------------+--------+----------+------+------30201           | 7237           | 1953 |
   1 |   1 |    230201           | 7237           | 1953 |        2 |   1 |    530201           | 7237           | 1953
|       3 |   1 |    030201           | 7237           | 1953 |        4 |   1 |   -3
 
.....

(Of course, thanks to Stephan Szabo for the method to obtain this from my 
strange source data. I didn't think this was possible.)

After have done this query I've realized that I need the data to be ordered 
by date. Do you have any suggestion?

Best regards
----------
Javier