Bomber jackets are the perfect midseason style piece, but they can be worn in any season really. For example, if you buy a thick bomber jacket as an outer layer for the winter and make sure you wear plenty of layers underneath, you'll be plenty warm. The only problem is that most bomber jackets are not normally waterproof, so if the weather’s really bad, you might need a better winter coat. However, many are water-resistant, so they do provide some light protection against rain.
While some models may be too heavy in warmer weather or early fall, there are so many options available that a thinner bomber jacket is easily acquired.