Brewer's: Neiges d'Antan
(The). A thing of the past. Literally, “last year's snows.”
“Where are the snows of yester-year?” Rossetti.
“The whole has melted away like the neiges d'antan.” - Nineteenth Century, June, 1891, p. 893.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894