Though the sun shines, leave not your cloak at home.

Favorable conditions now do not guarantee that they will last. It is wise to keep a useful safeguard available even when there is no immediate sign of trouble.

The proverb urges foresight rather than reliance on appearances. Its point is not to expect the worst, but to avoid discarding a sensible precaution simply because it is not needed yet.

Use it to advise someone who is about to forgo a reasonable precaution because the situation currently looks favorable, especially when conditions could change.