Now, of course, this all depends on where you live (i.e., how bad your summer climate will be), where you work (at a bank or at an advertising agency), and what dress code policies are enforced for your organization (open-toed sandals, sleeveless, hosiery, etc.) Not to mention whether your place of business keeps the air conditioning at a warm 75 or at a cool 65!
Obviously, the colors lighten and brighten up with the sun starts beating down. Black tights might work in January but come June, if you choose to or are required to wear hosiery, nude is a much better summer look.
I am a big fan of the short-sleeve cardigan since the Texas summers get hot outdoors but the offices tend to run their air conditioners very strongly. Likewise, a colorful sweater set is a great bet. I am a fan of the sweater set because you end up with several options from one purchase! You can wear the cardigan with a different outfit, the shell under a suit, or both together as the set. And FYI, these are marvelous to travel with because of that feature. Changing up the accessories such as scarves and statement necklaces can vary the entire look.
Most of my work slacks are gray or black, so I do not end up with much variety there, even from season to season. My variety must come from accessories or tops. And while I do not tend to wear skirts in the winter, I do have a handful that I break out when the thermometer starts rising.
Just remember to follow your boss’s lead – if she doesn’t wear sleeveless, you should probably avoid it as well. Same goes for the hosiery rule and the open-toed shoes.