Hot weather makes people dumber, angrier and less productive

As New Zealand suffers through a sweltering heatwave, you may be wondering how the weather is affecting your mood.

Unfortunately, the results aren't good.

It turns out the heat can play havoc with our temper, intelligence and productivity over summer, and make people angrier, dumber and lazier.

It shouldn't be too much of a surprise, but has been scientifically proven that excess heat can make people grumpier and even bring about more conflict.

A 2013 study from Stanford University found deviation from moderate temperatures and rainfall can increase conflict risk, with temperature having the highest effect.

According to the study authors, there is an 11.3 percent change in the chance of intergroup conflict when temperature changes and a 4 percent change in interpersonal conflict.

As for intelligence, well unfortunately, that goes out the door when it's hot too.

Simple intelligence tests in the heat can be hard, as some Sydney University researchers discovered, when they asked shoppers to recall unusual objects researchers had placed in a magazine shop.

The shoppers performed three times better when the weather was bad, compared to when it was sunny, with the gloomy weather allowing people to think more deeply and clearly without summer's distractions.

Speaking of distraction, hot weather also makes it harder to perform at work, with workers becoming distracted by the sunny weather.

Harvard University researchers looked at the productivity of employees at a mid-sized bank in Japan and found, when the weather was cold and rainy, the workers were more productive.

It turns out, when the weather is hot, the workers spent their time thinking about all the fun things to do outside, rather than their actual jobs.