This clause, “it was not the season for figs” in Mark needs to be taken in its wider theologic import and typology. Jesus, His disciples, and anyone else familiar with figs in Israel knows about breba figs- those trees which bear fruit early as a first crop just after winter time during initial leaf set. Here is a picture taken today in Israel one week before Passover (March 24, 2018) showing these early figs:
(picture credit: https://bleon1.wordpress.com/2018/03/23/caesarea-philippi-2/#comment-23904)
Attestation to breba figs in the O.T.: When I found Israel, it was like finding grapes in the desert; when I saw your ancestors, it was like seeing the early fruit on the fig tree. (Hosea 9.10 NIV)
Is. 28.4b: will be like a first-ripe fig before the summer; whoever sees it, eats it up as soon as it comes to hand. (NRSB)
All your fortresses are like fig trees with first-ripe figs—if shaken they fall into the mouth of the eater. (Na. 3.12 NRSV)
Song of Solomon 2.13a: The fig tree puts forth its figs, and the vines are in blossom (NRSV). Note that the grapes are in blossom in the spring season while the text has the fig tree setting fruit at the same time. All of these texts reference breba figs in the O.T. Therefore, the clause: “It was not the season for figs” needs to be explained to give understanding. The main crop of figs is after summer as Mark says, but in certain years some trees produce figs also in the spring in addition the the heavier crop in autumn. However, one indication of brebas is abundant leaf set in the spring season. Therefore, Jesus sees the abundant leaves as a sign of this early fruit, but finds the tree empty. This was like Second Temple Israel, very religious outwardly but no real fruit. So the statement of Mark, “it was not the season for figs” cannot be construed as an irrational motivation when Jesus subsequently curses the tree. Rather, this reasonable expectation by Jesus is turned into a trope to signal judgment upon the nation.