At any rate, what are usually called year-round suits are anything but. Too cool for winter and too warm for summer, mid-weight suits are generally made from 10 ounce/300 gram or lighter cloth, a reasonable weight for 3-6 months of the year depending on the local climate.The rest of the time they leave a man's legs too cold beneath his overcoat, or force him to remove his jacket in the heat of a New York subway (admittedly, sometimes even the lightest of suits are too warm for that environment). And mid-weights are unfortunately some of the least interesting suits a guy can have as well, being worsted wool generally. Some might be blended with a bit of mohair but woolen flannel and tweed cannot be woven as mid-weight cloth.
I do not know any of these year-round suit men so I can only imagine that they are new to bespoke tailoring and looking for something that will give them a lot of wear. Mid-weight suits will do that, in fact I have written before that they should be the first suits in a man's wardrobe. But they ought to be joined by lighter weight suitings for the heat, and heavier suitings for the cold as quickly as budget allows.
So order some flannels. There is no such thing as a year-round suit.
Illustration: Apparel Arts