I've thought about suggesting seasons before, they have been up for suggestion in HnH, one argument against them is what happens to a newbie who joins at the start of winter, my answer would be that they struggle on until spring.
I would've thought that first implementing weather, just a simple effect with different forageables available. Or even the random stuff, like you might find "a dazzling glint" when picking something if its sunny and brilliant honey-dew when its raining.
In HnH the time of day affected some foragables, as we don't have night and day, use weather.