Motorcycle riding is not limited to one season. Some days are hot, some are cold, and sometimes the weather changes while you are still on the road. This is something most riders deal with regularly.
Riders are directly exposed to wind, heat, and rain, unlike people who drive cars. This means that the gear you wear has a big effect on how safe and comfortable your ride is.
A 4-season motorbike jacket is one of the most useful things you can buy right now. You don't have to switch jackets all year long; you can just use one that works in most situations.
For more information, read the blog: https://jagwear.com/blogs/blogs/guide-to-year-round-motorcycle-jackets