The heat and humidity, the cold or a weather front moving through can all trigger the headaches, says neurologist Dr. Alan Rapoport, director and founder of The New England Center for Headache in Stamford, Conn. About 30 million Americans have migraines, which is a severe kind of headache that can virtually immobilize a person.

"Patients don't really understand if weather is a factor," says Rapoport, the study's co-author. "We were very surprised when we asked patients in advance if they think weather affects them -- 85 percent did. Yet, our study showed only 51 percent were affected."

Even though the "many patients who think they are sensitive to weather aren't, that [51 percent] is still a significant number," adds Rapoport.

The research team followed 77 patients for an average of 11 months, having them keep track, three times a day, whether or not they had a headache, and the pain level on a scale of zero (no headache) to 3 (the worst headache.)

The researchers then analyzed government weather data and looked for correlations:

• Twenty-two percent of the patients were sensitive to low temperatures and low humidity;
• 12 percent had migraines triggered by high temperatures and high humidity;
• A passing front or otherwise-changing weather pattern affected 10 percent; sensitivity to high barometric pressure affected 8 percent, and low pressure affected 5 percent.

"For many years, we have known that weather changes can act as triggers for migraine attacks," says Dr. Seymour Diamond, director and founder of the National Headache Foundation. However, he adds, "previous studies have shown that barometric pressure changes, rather than the combination of low humidity and cold weather are responsible."

"Many factors have to be considered in the genesis of migraine headache," adds Dr. Jerome Goldstein, director of the San Francisco Clinical Research Center and Headache Clinic. "Because migraine headache is a multifactorial process with a genetic propensity, conditions such as weather, allergies, stress, menstrual flow, food and alcohol [to name a few] can either trigger or make migraine headaches worse."

As a follow-up, Goldstein suggests a study to compare the weather findings "to folks who have migraine headache primarily when in an airplane or those who ascend the Western Mountain regions in a few hours. These would certainly add validity to this report." These conditions would mean a rapid change to low barometric pressure, possible low temperatures and low humidity.

Rapoport adds that, although many other things can trigger migraines, he's confident the wealth of data available and the length of the study is enough to cancel out other variables.

"We don't know what [it] is in the weather yet," says Rapoport. "We think it is related to brain function, perhaps changes in the receptors that monitor brain function or temperature of the blood, but it's pure speculation."

"We're only beginning to know the weather pattern," he adds. This data "will help us analyze what factors make patients sensitive and what forms of treatment are best for the weather patterns."

The results of the study are being presented this week at the 10th International Headache Congress, of the International Headache Society.

What To Do

Not all headaches are migraines. Before medicating for the pain, check with your doctor and get a complete workup. "Seek medical consultation when a headache problem is new or an older headache problem is increasing in severity or when a headache problem is accompanied by new symptoms," says Goldstein.

If your headaches are frequent, try to figure out what may be triggering them. Keep a diary of what foods you eat, your moods, what you were doing when the pain began

And don't forget a weather diary. "Every day the patient should write down whatever they think is very important, the weather conditions, the temperature, the humidity, the absolute barometer pressure and the direction the barometer is going in," says Rapoport. "Then, look back over the last three to four months and see if you can pick out a pattern," and take it to your doctor.

Get more information about migraine headaches from the National Migraine Association or the National Headache Foundation.

Learn the language of headache with the migraine glossary.

Reference Source 101