If the ash before the oak comes out, There has been, or there will be drought.

The saying links the order in which two trees produce leaves with dry weather. If ash leads oak, it treats that observation as a sign of drought.

Its prediction points in both directions: the drought may already have occurred, or it may still lie ahead. The proverb expresses a traditional weather belief, not a dependable test.

Use it when discussing the order in which ash and oak come into leaf, especially as an example of reading weather signs from trees. Present the drought connection as a belief rather than a reliable forecast.