The quality of being appropriate for a particular season, like winter, spring, summer, or fall.
Seasonablenesses are good because they mean things are right for the time of year.
Examples:
The seasonablenesses of the clothes in the store are perfect for summer.
I like the seasonablenesses of the decorations in the fall.
The seasonablenesses of the food at the party were just right for winter.
The seasonablenesses of the swimsuit in the winter made everyone laugh.
The seasonablenesses of the snow in the summer would be very strange.
The seasonablenesses of the flowers in the winter were very surprising.