He answered ... - The meaning of this answer is, There are certain indications by which you judge about the weather.

In the evening you think you can predict the weather tomorrow. You have evidence in the redness of the sky by which you judge. So there are sufficient indications on which you should judge concerning me and these times. My miracles, and the state of affairs in Judea, are an indication by which you should judge.

Is red - Almost all nations have observed this as an indication of fair weather.

In the morning ...the sky is red and lowering - That is, there are threatening clouds in the sky, which are made red by the rays of the rising sun. This, in Judea, was a sign of a tempest. In other places, however, the signs of a storm may be different.

The face of the sky - The appearance of the sky.

When it is evening - There are certain signs of fair and foul weather, which ye are in the constant habit of observing, and which do not fail. - The signs of the times: the doctrine which I preach, and the miracles which I work among you, are as sure signs that the day-spring from on high has visited you for your salvation; but if ye refute to hear, and continue in darkness, the red and gloomy cloud of vindictive justice shall pour out such a storm of wrath upon you as shalt sweep you from the face of the earth.

He answered and said unto them,.... Knowing full well their views, and having wrought sufficient miracles to confirm his Messiahship, he thought fit to give them no other answer than this:

when it is evening, ye say, it will be fair weather, for the sky is red; when the sun is setting, it is a common thing for you to say, looking up to the heavens, and observing the face and colour of them, that it is like to be fair weather; no rain, that night, nor perhaps the next day, for the sky is red like fire, through the rays of the sun; which show the clouds to be very thin, and so will soon waste away, and consequently fine weather must follow.

Fair weather (εὐδία)

Colloquial. Looking at the evening sky, a man says to his neighbor, "Fine weather:" and in the morning (Matthew 16:3), "Storm to-day" (σήμερον χειμών).

He answered and said unto them, When it is evening, ye say, It will be fair weather: for the sky is red.

16:2 Luke 12:54.

16:1-4 The Pharisees and Sadducees were opposed to each other in principles and in conduct; yet they joined against Christ. But they desired a sign of their own choosing: they despised those signs which relieved the necessity of the sick and sorrowful, and called for something else which would gratify the curiosity of the proud. It is great hypocrisy, when we slight the signs of God's ordaining, to seek for signs of our own devising.