Mat 16:3 And in the morning, foul weather today: for the sky is red and lowering. Oh, you hypocrites, you can discern the face of the sky; but can you not [discern] the signs of the times?

When I read this in English, I thought the "time" would be aiôn, the Greek word most often used in the New Testment meaning this age, this generation, or our times. However, Christ is saying something much more specific here. The word he uses for "time" is kairos, which has the sense of a critical point in time. The word for "sky" here is, as in the last verse," the same word used for "heaven." So Christ is saying that we can distinguish the appearance of heaven, symbolically, what God wants, but we cannot see the critical junctures or decisions in our lives.

"Foul weather" is from cheimôn, which means "winter" or "wintry, stormy weather."

"Lowering" is from stugnazô, which means "to have a gloomy, lowering look."

"Discern" is from diakrinô, which means "to separate," "to discriminate," "to distinguish," and "to decide." It captures the idea of telling one thing from another. It also means "to question" or "to doubt." In the Gospels, it is most often translated as "doubt" and second most often translated as "judge."

"Face" is from prosôpon, which means "face," "front," and "facade." It generally means the appearance of things.

"Sign" is from sêmeion, which means "sign," or "signal.

"Times" is from kairos, which means "due measure," "fitness," "measure," "vital part," "exact or critical time," "opportunity," and generally, "season." There is a sense in the word of a special time or point, rather than any time or place.