What jacket should men wear in spring and autumn?

Bombers, hooded windbreakers, light fleece-lined jackets and shirt jackets all work well in spring and autumn. In colder weather a quilted jacket is the better choice, and in wind or rain a functional hooded jacket.

At what temperature should you wear a transitional jacket?

A transitional jacket is meant for moderate cold, when temperatures drop below the mid-teens Celsius but it is not yet freezing. In freezing weather a padded winter jacket or parka is a better choice.

What is a shirt jacket?

A shirt jacket, or overshirt, is cut like a shirt but made from heavier fabric and worn as outerwear. It goes over a T-shirt, a long-sleeve top or a thin jumper.