Not the weather.
In Matthew Chapter 16. verse 1. We find the Pharisees and the Sadducees asking Jesus for a sign from heaven
2. He answered and said to them, when it is the evening you say it will be fair weather for the sky is red.
3. And in the morning it will be foul weather today for the sky is red and threatening. Hypocrites!. You know how to discern the face of the sky, but you can not discern the signs of the times.
But that was all they knew, but we have an advantage over them. We have the Holy Spirit who teaches us all things in spirit and in truth. We can ask him about something we are not sure about and he will give us an answer. We can then discern which way we should walk with him.