A Shade Lighter
I’m a big believer in dressing seasonally. Consider a simple, basic pairing: a blue oxford cloth button down shirt with a mid-weight navy wool blazer. It’s a classic combination that can be relied on year-round. But in the fall and winter months, this can be switched into a cotton/wool blend flannel shirt and tweed jacket, and then in the spring and summer, changed into a madras shirt and linen sport coat. The OCBD and navy blazer can be always worn (well, depending on the harshness of your climate), but the other pairings will better reflect the moods of their respective seasons.
Dressing seasonally can also mean adjusting your color palettes. For spring and summer, this can be as simple as wearing things just one shade lighter. So instead of a navy sport coat, consider Royal Air Force blue or French blue. Instead of dark brown shoes, consider chestnut or tan. Instead of dark grey suits, consider a more summery dove grey. These can all be the same exact garments, but in being one shade lighter, they’ll automatically feel more in harmony with the season.