Now I know why motorists in Continental cities behave so badly – why, in Rome, Madrid, and Athens, they shout and sound their horns like there’s no tomorrow.

It’s the warmer climate.

The recent heatwave – however short – turned the roads into melting pots of aggression. Drivers snarled and scowled at each other. Even those standing stationary at the lights looked ready to blow.

There’s nothing like a hot spell to spark a spot of road rage. According to a survey, half of all tired, hot motorists will vent their frustration on other road users at least once a week as temperatures soar. A quarter will use bad language, 40per cent will make rude gestures and one in five will go as far as tailgating.

I haven’t gone that far – I don’t fancy a self-induced spell in A&E – but I do yell at the kids a lot more when we’re stuck in traffic in the heat. Their choice of radio station – wall-to-wall chart hits with a lot of drivel in between – annoys me more than usual, so does the constant opening and closing of windows and arguments over bottled water.

Hot vehicles don’t bring out the best in people. Neither do hot trains. When I squeezed into the jam-packed carriage that took me home from work during the hot spell, everyone was sounding off to staff about the service, asking to upgrade to a cattle truck.

Normally, we all just put up with it. Generally, you can find a tiny space, take out your paper and forget the discomfort. But in extreme temperatures you can’t.

Commuters are sweaty, sticky and often smelly, and they can’t keep still. They thrash about, wrestling with windows, fanning themselves – and everyone else – with newspapers, and cracking open cans of drink showering those around them.

The survey, by Travelodge, found that more than during a heatwave one in five short-tempered rail, tube or train commuters will make a rude comment to another traveller while 15per cent will end up arguing with staff. More than a quarter will shout at a partner or child while travelling.

I almost snapped at the rail commuter who ate a peach and left the messy remains on the table in front of me last week, only I thought I recognised him from Inside the World’s Toughest Prisons.

People are on far shorter fuses in hot weather largely because of sleep deprivation. On hot, humid nights almost 90per cent of us lose on average two-and-a-half hours sleep, making us moody and irritable during the day.

We should look on the bright side, though, we’re all saving on heating bills.