Weather systems can spark migraine attacks, neurologists have found.

Scientists at the University of Calgary in Canada have come up with evidence for what migraine sufferers have said for years - that the weather can act as a trigger for their condition.

Their study, published in Neurology, the publication of the American Academy of Neurology, looked specifically at the links between migraine and the occurrence of Canadian Chinook winds.

Author Werner Becker, MD, of the University of Calgary, said: "Chinooks are ideal for studying a link between a weather change and migraine because they have a definite time of onset and are a profound weather change."

Chinooks are warm westerly winds which occur in Alberta, Canada.

Researchers studied the diaries of 75 migraine patients at the University of Calgary Headache Research Clinic, and compared them to Chinook weather patterns.

The patients had recorded the severity of headaches, and the time of day that they happened.

Of the 75 patients studied, 32 were more likely to have migraines during Chinook weather conditions than on days without Chinooks.

Dr Becker said: "Identifying trigger factors for migraine, like the Chinooks, can help neurologists treat, manage and learn more about the causes of migraine.

"The more triggers we can identify, the closer we get to preventing the onset of migraine.

"Patients could treat migraines before they start, similar to those patients who suffer from menstrual migraine."

Of the 32 Chinook-related migraine patients, 17 were more likely to get migraines days immediately prior to the onset of the Chinook.

Older patients

The remaining 15 patients were more likely to suffer on high wind days when the wind velocity could reach 24mph. Only two patients got migraines under both conditions.

Neurologists concluded that the Chinook therefore probably contained two separate triggers for migraine.

The scientists also found that older patients were more likely to suffer migraines on high wind Chinook days than younger patients.

But Dr Becker said: "How Chinooks trigger migraines is still unknown."

Known trigger

He added: "Most people believe weather affects their health. Overall, approximately 50% of migraine sufferers indicate certain weather condition may precipitate migraine attacks.

"This study validates what patients have been saying all along."

Sue Rayner of the UK's Migraine Action Association said that there were many different types of trigger for an attack.

She said: "We encourage sufferers to keep a diary and write down everything they have done and eaten, and everything that has happened to them for about 36 hours around an attack.

"Things like tiredness, hunger, flashing lights, food - absolutely anything can trigger a migraine and every sufferer's triggers are different.

"However, we do encourage people to make a note of weather conditions because they are a known trigger."