This is a pleasant little waltz with an air of nostalgia surrounding it. Un Jour de Septembre has a nice melody floating all the way through firstly in A minor and then a more dramatic change comes with the arrival of the mid-section in G minor and finally a return to the original key. The piece doesn't really have any surreptitious surprises with regard to melody or harmony; it just floats along nicely in an unpretentious fashion.
Steve Marsh (Classical Guitar Magazine)
Interactive score on Guitar by Masters website:
https://www.guitarbymasters.com/bookprofile/278