Matthew 16:2

But he answered and said unto them, When it is evening, ye say, It will be fair weather: for the heaven is red. And in the morning, It will be foul weather today: for the heaven is red and lowering. Ye know how to discern the face of the heaven; but ye cannot discern the signs of the times.

This was not an endorsement of the Pharisees' method of predicting the weather, but was a glaring contrast, pointed out by Jesus, between their supposed sagacity in material things and their blindness to far more important spiritual things pertaining to the kingdom of heaven.

What are "the signs of the times"? (1) The prophetic weeks of Daniel were about to expire. (2) The great herald of the new age, John the Baptist, had appeared according to prophecy, "in the spirit and power of Elijah." (3) The scepter had departed from Judah and the lawgiver from beneath his feet (Genesis 49:10). (4) Even a "sign from heaven" had already been given at the baptism of Christ when God spoke out of heaven, saying, "This is my beloved Son, in whom I am well pleased" (Matthew 3:17). (5) It had been revealed to Simeon that he should not die until he had seen the Lord's Christ; and it must be presumed that Simeon, by that time, was long since dead and buried. (6) All the world was expecting the coming of some Great One. (7) The Christ himself, "that Prophet like unto Moses," had appeared upon the banks of the Jordan and had been identified by John the Baptist as "the Lamb of God that taketh away the sin of the world"! And John was the only authentic prophet Israel had had in half a millennium. Yes, it must be admitted that the Pharisees missed the signs of the times, however skilled they might have appeared as weather prophets!