make hay while the sun shines
Hay harvest can be spoiled by wet weather. It is important that farmers seize the opportunity of dry weather for haymaking tasks (cutting, drying, gathering). Especially in medieval times, when forecasting the weather several days in advance was more difficult, it was all the more vital. Attested since 1546, originally a Tudor expression, and used figuratively since 1673.
- (literally, agriculture) To make hay during favourable (dry) weather.
- (idiomatic) To act while an opportunity exists; to take action while a situation is favorable.
In the imperative form, this verb is used as a proverb.
- (imperative) To act when an opportunity is only for a limited time.
- Gregory Y. Titelman, Random House Dictionary of Popular Proverbs and Sayings, 1996, →ISBN, p. 225.