Summer formal can be quite the challenge for the fashion-conscious guy. You want an outfit that looks put together, but at the same time is comfortable enough to get you through a three-hour event outdoors in the eighties. It's not an easy balance to strike, but it's achievable with the right approach and a few summer-friendly pieces. Lighten Up
If you're yet to own a neutral color suit, buy one. The lighter color always works well for spring and summer, regardless of whatever might be the trend. It's a relatively casual color, however, so it won't fly at strictly formal affairs.
A black tie dress code might require you to rent (or buy) a pastel color tux, especially if it's an outdoor event. The darkness of the color is proportional to the heat that the fabric absorbs, so there's a very good reason to invest in a lighter color. Pastel blue works particularly well because it's an easy color to pair, but is distinct enough from white so that you'll never be mistaken as the groom.
Brighten Up
For all the comfort that they offer, light colors are not without shortcomings. Any outfit styled in predominantly pale or pastel shades will most likely end up feeling lifeless or dully faded. Basic pieces in brighter colors should keep your ensemble both lively and interesting.
Instead of a pastel shirt, try on one that has a bright and well-saturated shade. Milder colors like sea blue and lilac are perfect for this because you can turn up their volume without the shirt becoming too distracting or noisy. As an alternative, you could use bright accessories like a lively necktie or bow tie to refresh a softer colored shirt. You could even throw in a pocket square in a similarly loud color for good measure.
One thing you should know about bright colors is that they ought to be used sparingly - only at a time, when possible. Don't make the mistake of wearing bright on bright (or, worse, bright on bright on bright). Even such seemingly tiny details as bow ties and pocket squares can already be very dramatic.
Loosen Up
The heat of summer can make moving around very uncomfortable, so it's not wise to compound this with tight clothing. Although fitted shirts and pants are ideal for formal fashions (and most other kinds for that matter), looser fits are a good middle ground between comfort and style.
Start by examining your shirt, which is often the first victim of too much heat and too little antiperspirant. Look for ones that have a bit more space than usual around the arm holes and the chest. These are most commonly the problem spots when your sweat glands refuse to cooperate with you. An undershirt is critical in these kinds of events, but you probably knew that already.
Be a real man and learn to tie a real necktie or bow tie for yourself. Aside from ready-made ties being too infantile for any man past high school age, a real knotted tie is easier to undo and pull off when it gets too warm. A grown guy stuffing an elastic banded tie into his pocket is simply undignified.