New Revised Standard Version
He answered them, “When it is evening, you say, ‘It will be fair weather, for the sky is red.’

Contemporary English Version
He told them: If the sky is red in the evening, you say the weather will be good.

New American Bible
He said to them in reply, “[In the evening you say, ‘Tomorrow will be fair, for the sky is red’;

Douay-Rheims Bible
But he answered and said to them: When it is evening, you say, It will be fair weather, for the sky is red.

But he answered and said to them: When it is evening, you say, It will be fair weather, for the sky is red.

When.

Luke 12:54-56 And he said also to the multitudes: When you see a cloud rising from the west, presently you say: A shower is coming. And so it happeneth. . . .