In Queensland it is known as “going bananas”; in the neighbouring Northern Territory they call it “mango madness” and elsewhere they simply “go troppo”.

Every October and November as the monsoon approaches, inhabitants of the top end of Australia are - often rudely - reminded of the apparent link between soaring temperatures and equally rising tempers.

The suspicion is nothing new. In the 1st century BC the Roman philosopher Cicero lamented: “The minds of men do in the weather share, dark or serene, as it's foul or fair.” Now surgeons at the Royal Darwin Hospital who analysed facial fracture rates have concluded that the period of extreme heat, leaden skies but little rain, provokes a surge of violence.

In an analysis presented to a medical conference in Hong Kong this week, the doctors showed that fractures resulting in hospital treatment were 40 per cent higher in the months when daily minimum temperatures at night were highest, humidity peaked and the rainfall and hours of sunshine were lowest.

“It's also when the mango is harvested, so now it's official,” Dr Mahiban Thomas, the surgeon who led the study, said. “When there are mangoes in the markets there is madness in the streets.” The Northern Territory, a vast and remote land that occupies much of the centre of the continent, climatically has more in common with Singapore than Sydney. Temperatures rise to about 30C most days in October and November when shirts stick to the skin and humidity hits 70 per cent - at 9am. Then into the steamy mix is poured alcohol: the Northern Territory has the highest rate of alcohol consumption in Australia.

The Australian Institute of Health and Welfare says that the rate of injuries from assaults in the region is at least five times higher than the national average. Nine in every ten facial fracture admissions are the result of violence. Dr Thomas and his team studied monthly hospital admissions over the 12 years to 2006 and plotted them against historic weather data on temperature, humidity, rainfall and sunshine.

There were 15 to 20 admissions in most months but consistently more than 30 in October and November.

“Hot nights spell trouble when there's all that warmth but no rain to relieve it and bring the tension down,” Dr Thomas said. “We can't do anything about the weather, but now we've proven the trend we can at least be prepared for it when October rolls around.” Dr Mathew Brambling, a lecturer in psychology at Queensland University of Technology, says it may be no coincidence that the Northern Territory ranks second worldwide in hospital admissions of facial fractures behind Greenland, which is cloaked in extended periods of darkness.

Shorter, darker days could affect the secretion of neurochemicals involved in mood, giving rise to the condition called seasonal affective disorder, also known as SAD, he said. Heatwaves had been found to increase aggression, impulsiveness, risk-taking behaviour, violence and suicide.

“It's important not to forget the behavioural side of this. Particularly up in the top end of Australia, it is very hot and people do a lot of drinking. The research is clear that alcohol is involved in most violent crime,” he said.

“What do you do if it's a stinking hot day? The air-conditioned pub looks pretty good.”

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