The parable of the fig tree explains this.

Now learn a parable of the fig tree; When his branch is yet tender, and putteth forth leaves, ye know that summer is nigh:

In the Apocalypse of Peter, Peter holds a dialogue with Jesus about the parable of the fig tree and the fate of sinners.

Christ tells us that we should learn from the parable of the fig tree - "when its branch has already become tender, and puts forth its leaves, you knew that summer is near" (Matt.

And so Jesus shared six parables with them; the parable of the fig tree, the porter, the master of the house and the faithful and evil servant, the ten virgins, the talents and the sheep and the goats.