Seasons
Seasons are an optional feature that can be enabled in the world setting before creating the world or in the settings after world creation. There are 4 seasons in game, Winter, Spring, Summer and Autumn, all seasons start and end on 22nd of February, May, August and November.
Effects on Gameplay
When seasons are enabled, gameplay is affected in a few ways:
Crops - With seasons enabled, crops can only be planted in the Spring, between February 22nd and May 22nd. Once crops are harvested, they must all be taken out of the field and put into storage or processed in a factory before Winter (November 22nd) else the crops will wither and be destroyed.
Heating - With seasons enabled, a new resource called heating is enabled too. Heat must be supplied to buildings like residential structures, stores, education facilities, hospitals, etc. Without heating, citizens will get sick and either die or flee your republic.
Leisure Activities - During the winter months, outdoor facilities like the Beach, Football Playground and Tennis Playground are closed. This requires the construction of indoor pools to satisfy the Sport Enjoyment Stat for citizens.
Roads - During the winter months when it begins to snow, roads become covered in snow. This significantly reduces the maximum speed of vehicles. On Mud Roads, the maximum speed is reduced to 13 km/h; on Gravel Roads, the maximum speed is reduced to 23 km/h; on Asphalt Roads, the maximum speed is reduced to 38 km/h. This effect can be reversed by keeping roads plowed using Snowplows, which are dispatched from Technical Services buildings.