Yesterday, with temperatures expected to climb in the high 90s in New York, Discovery sent out an email to employees encouraging them to dress "business comfortable". The notion of ditching the tie in summer is becoming more usual in the business world as well.
Both are acknowledgements that European business dress, now adopted around the entire world largely regardless of local climate, is entirely ill-suited for temperatures above something in the range of 75-80°F, depending on personal preference, and cut and material of the suit.
Opening up the collar surely is a good thing in the heat—after all the modern necktie is the long lost relative of neckwear worn by Roman legionnaires for the purposes of staying warm. It's a diminutive yet very warm scarf, tightly wrapped around the neck, and not intended to absorb sweat.
But in the same vein as recommending that we ought to be working with the natural rhythm of the day and the heat and not just powering through it or attempting to overly control it, as well as accepting that sweating is a perfectly normal and acceptable human function in truly hot weather, I propose this: Let's go well beyond simply ditching the tie or dressing business comfortable in hot weather. Let's redefine entirely what's considered acceptable dress in the heat of summer.
I'll confine myself to men's dress, for the sake of talking about what you know personally.
Consider for a moment the way traditional dress has evolved around the world in places where temperatures we complain about in much of the US as abnormal hellish abominations (which we're helping create, it deserves repeating, through burning of fossil fuels) are simply normal, long-standing climatic patterns.
In dry hot arid climates (think the Sahara, Arabia, parts of north and western India and Pakistan) traditional dress actually covers the entire body, often the head as well. Though some level of cultural modesty is involved in some places, at the heart of this is really defense against the sun.
I can tell you from personal experience in 110°F+ temperatures, with little humidity, that the advantages of keeping the head covered by a loosely draped cotton scarf in terms of sun protection far outweigh all other factors. Ditto for actually keeping the arms and legs fully covered with loose-fitting, airy, breathable clothing. It's all about the sun and protecting the body. If there's a breeze, such garb actually grabs some of the wind and helps cool.
In more humid and hot climates though things change.
First of all, temperatures in such places (I'm thinking south India, Indonesia, South-East Asia), though surely hot, don't usual rise nearly as high as hot dry climates. Though it equally surely may feel worse at times due to the humidity if you're not accustomed to it. All of which is to say that the sun, while still a factor, isn't as much of one as in even hotter dry places.
In a wide swath of land from Africa through Asia where such conditions are common the traditional dress of men is, in one local name or other, a sarong. Just loose cloth, sometimes stitched into a tube, sometimes not, wrapped around the waist and tied. It's simple, green (less material than trousers and less energy in manufacturing), comfortably airy and often very stylish. Though today going without a shirt doesn't happen unless you are a laborer, historically men forsake top covering altogether (save, in some places, another loose piece of cloth wrapped, not stitched)—as did women, before Victorian and Muslim prudishness took over.
In Polynesia, Amazonia, equatorial Africa local traditional clothing equally developed, at least partially, in response to constant heat and/or humidity.
Now, I'm not suggestion those of us used to dressing in derivatives of European fashion just wholesale adopt some traditional dress from another part of the world.
Rather I think we ought to take heed of what people in historically and consistently hot places have done in clothing to keep cool, before air conditioning started turning the world (at great expense, financial and environmental) into a 68°F sameness. We have plenty of examples of low tech, energy free ways to beat the heat all around the world.
We just have to break the mindset of assuming throwing more energy at the problem is the best way forward, as it seldom is.