Jamieson, Fausset and Brown on Ecclesiastes 11:3

3. clouds--answering to "evil" (Ec 11:2), meaning, When the times of evil are fully ripe, evil must come; and speculations about it beforehand, so as to prevent one sowing seed of liberality, are vain (Ec 11:4).

tree--Once the storm uproots it, it lies either northward or southward, according as it fell. So man's character is unchangeable, whether for hell or heaven, once that death overtakes him (Re 22:11, 14, 15). Now is his time for liberality, before the evil days come (Ec 12:1).