Do not wear white after Labor Day.

Of all the rules, not wearing white after Labor Day in the US is the most disconnected from its intention.

Yet it is fervently followed. Wearing white attracts the ire of many people who would otherwise have no opinions on correct dress or style. They certainly would not point out that notch lapels are anathema on a tuxedo.

For example, in an online discussion on this rule, one person comments: “White should never be worn between Labor Day and Easter. It is called good manners. Only the ignorant of decorum would say…oh, it doesn’t matter. It shows how much education and attention to propriety a person has. Only break the rule if you want people to think you do not know any better.”

Can you feel the vitriol spattering up onto you?

The reasoning behind the rule is simple. You wear white in the summer because the weather is brighter. It is usually sunnier, the sun is higher in the sky, and so it is generally brighter. And light-coloured clothes suit brighter weather, just like dark colours dominate evening events.

Other light colours are equally summery – tan linen jackets, seersucker suits, spectator shoes – and suit brighter weather.

But that doesn’t mean it’s never bright in winter. Indeed, the frosty and blue-skied days of December often seem the brightest, if only by contrast to the leaden days that surround them.

White is the lightest of colours and therefore only suited to the brightest of days.

In order to make it easier to communicate about the harmony of colours and weather, a rule was invented: only wear white in the summer months, here defined as between Easter and Labor Day. Like all rules, it loses in nuance what it gains in immediacy.

Once you know why that rule exists, it is easy to break it with impunity. Winter whites can look simply lovely, although creams and off-whites will generally be most practical and flattering.

Trousers are probably the easiest rule-breaker to go for, as they are after all not far off the ubiquitous American chino in colour. I’d go for jacket next, with shoes last.

It is no coincidence that this rule is dominant in the US, yet barely known in the UK.

The weather in much of the US, particularly the east coast, is consistent enough to link sun with particular months, and so produce a sensible rule. In London, where you are just as likely to have grim rain in July and a week of sun in January, the rule seems absurd.

That is what the rule means, and understanding it allows you to break it intelligently. Wear white when it’s bright.