What are the seasonal changes of the tundra biome?

The tundra has two main seasons.

During the cold season, winter, which lasts from late fall through winter, and into early spring. The temperatures during the cold season is around 18 F, 28 C, below zero, and it can be dark for much of the cold season without any daylight, depending on how close you are to one of the poles.

In the warm season, summer, temperatures are around 12 C, 54 F. This isn't warm enough to thaw the permafrost layer, however. During the summer, plants like lichens, small berries, grasses, and moss can grow. And because the tundra is so close to the poles, for a portion of summer there is 24 hour daylight for several weeks.