Where do I find the length of the seasons in Rokugan?

Rokugan has a rather large canon lore, and I am a little dumbstruck when trying to sift through all of them for the information I seek about the climate of Rokugan.

In particular, I try to find out when the seasons are changing, and if Rokugan does feature a "rainy season" like Japan, which is kind of an addition to in between Spring and Summer there. For example, the year 2019/20 has the following dates for its seasons in Kyoto Area:

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