I fully agree with the assessment from KLouis. But just to add a bit, even if you hit bad weather on Crete, from my own experience living on the island, it is often easy to escape it in Autumn or Spring. Due to the geography of the island, with a mountain chain running along the spine from the west to the east, you will often find the winds from the north that are most likely to bring the rains. If this happens, chances are quite big the plains among the northern part of the island (where the vast majority of people live) will have rain, but when you travel to the southern coast across the mountains, you can easily find blue skies and sunny weather when at the other side. Keep this in mind when being based in the north and visiting places on the southern coast like Preveli, Paleochora, Sfakia, Loutro etc.