Upvote:1
The factors that influence the time of harvest are:
The lighting difference for Cyrenaica and Greece is practically insignificant - they both are far from poles.
The points 2 and 5 depend on the slow longtime changes of the climate and thus are the subject of history. For nowadays Cyrenaica is the part of dezert or very close to it. And it was not in the antic times. So, the agriculture timings now are much more strict. And the time for riping is longer, than in Greece, if you do not water the culture. So, nowadays, it is not so sure about earlier harvesting in Cyrenaica. On the contrary, you could wait for your wheat forever.
As for the antic times, when the Northern Africa grew the wheat for the whole Rome Empire, the desert regions were far from the coast. The region was only somewhat dry.
The temperatures of 350BC, according to 1850-year cycles, should be similar to these of 1500AC, or were at the lower end. So, the winter should be noticeable. And Cyrenaica's inhabitants had to adapt the starts/ends of agriculture cycles to the same season changes, as in Greece. Of course, you are absolutely right, the warmer weather meant earlier spring seeding and harvesting. The dry summer moved the harvesting time in the same direction. They in Cyrenaica had to harvest their spring wheat much earlier.
It is not so simple with the second harvest. I am not sure Greece had one in that climate. So, it is unclear, what is to be compared.
And I don't know if Cyrenaica had enough summer rains to seed wheat in July and not to wait for the September rains.