One region on my Kepler Bb earth-like world has a total of 8 seasons for some physical reason. 4 of those are transition phases.
Calendar Divisions
Their year begins on the first day of spring and their months with 9 day weeks are 65 days long. But that is just in Kepler terms. Their day is $2 \frac{2}{9}$ earth days long. Now I made it so that in terms of months, each transition phase is 2 months long and the other seasons are 3 months long. You can see that a year lasting 1155 earth days should probably be chopped up into more than four parts.
Moons
The planet has four moons in resonance with each other and would at most wobble the axis by a fraction of a degree or some insignificant number. I've decided this axis wobble is too insignificant to be the cause of the transition phases.
Seasons
Names for transition phases simply form from the 2 seasons each one is between. So here are their seasons in sequence through the year:
Spring: Most plants start growing on the first day of Spring, Cool to Warm weather, a lot of rain, a lot of sunlight.
Sprummer: First transition phase, Weather starts to get hot towards the end, essentially their equivalent of our May.
Summer: Hot weather, A lot of plant growth, dry spells for up to a week after a storm.
Summer Fall: Weather starts to cool down and some tree leaves start changing color but very slowly here, essentially their equivalent of our September.
Fall: Warm weather at the beginning, gradually getting cooler until it gets cold, a lot of color change, sometimes a sudden spike to summer temperatures for a few days to a week.
Fallter: Cold weather, Last bit of color change, snow starts falling.
Winter: Cold weather, no more growth or color change, lots of snow.
Winter Spring: Cold to cool weather, some plants start growing in the snow, essentially their equivalent of March
I'm seeking a physical reason to explain eight well-defined seasons. Axial tilt alone can not make 8 seasons instead of 4. Why else could there be 8 seasons like this?