Maybe because, unlike in the Mediterranian regions, spring and summer of the temparate climat are not that clearly distinguishable? From around May we could call the season summer.
Eén zwaluw maakt nog geen zomer. Identical to the English expression.

(meaning in summer there may be still be spring's temp. and in spring summer's, while in Greece the summers are blazing hot.)

Last edited by BranShea; 01/18/2008 11:25 AM.