One of the more frustrating aspects of migraine treatment is the unpredictability with which migraines tend to strike. Eliminating triggers and keeping an accurate headache diary are two of the most helpful things a patient can do, along with supportive medical treatment, but some days it seems as if migraines attack for no apparent reason. They can be as irregular as the weather!

What does the weather have to do with migraines? As it turns out, seasonal variations in temperature, brightness, humidity, and a host of other factors can be a very good clue into migraine patterns. In a study conducted in Norway, researchers conducted a survey of 169 female migraineurs. Norway is located on the edge of the Norwegian Sea, and straddles the Arctic Circle. Because of its extreme north location on the globe, Norway experiences brighter than usual sunlight during the summer months and the “midnight sun” phenomenon, where the sun is visible twenty-four hours a day in midsummer. The study concluded that a significant percentage of migraineurs suffered attacks due to overexposure to sunlight and that the amount of exposure to light was a contributing factor to the number and intensity of migraines experienced.

Most research shows consistent results when it comes to the effects of weather, humidity, and air pressure on migraines. In a 1999 study conducted by the Robbins Headache Clinic in Illinois, it was shown that 47 percent of female migraine sufferers (and 34 percent of men) felt that changes in weather precipitated a migraine. Forty percent of women (and 31 percent of men) noted sunlight as a migraine trigger as well.

Many migraineurs note seasonal variations in migraines — more headaches tend to appear during the fall and spring seasons. It is generally thought that changes in air pressure are to blame for the increased prevalence of migraine attacks during specific seasons. Rigorous reading of a barometer can help predict when seasonal migraines may occur and can give the migraineur additional preparation for a possible attack.

Sudden changes in air pressure appear to trigger migraines in many individuals. Average air pressure at sea level is 29.92 inches. When reading a barometer on a “typical” day near sea level, the needle (or digital display) will read around 29.9. On cloudy days that signal rain (often encountered in the fall), barometric pressure drops. Conversely, on clear and calm spring days, barometric pressure rises. While you cannot change the weather, you can change your routine and medication to account for variations in air pressure.

Note that no specific weather (sunny or cold, rainy or snowy) appears to have a consistent effect on migraine patterns. According to research conducted at the New England Center for Headache, it is the change in temperature, humidity, and air pressure that seems to trigger an attack. For example, a rainy day (with little sunshine) that is followed by a bright day (with many hours of bright sunlight) can provoke an attack. This insight can be used preventatively, allowing migraineurs to carry medications following weather conditions that are potential triggers. The preventative medications can then be taken at the first warning sign of a migraine.

Seasonal allergies are another potential migraine trigger. When pollen fills the air, those who are sensitive to it suffer from inflamed sinus passages. If allowed to fester, this condition can easily lead to a sinus headache, characterized by pain and pressure in the face and upper jaw. The inflammation, called sinusitis, thus causes a sinus headache that can, in some cases, trigger a migraine.

Avoid getting to the point where pollen and blooming vegetation cause a sinus headache. If itchy and watery eyes, sneezing, and a stuffy nose accompany the arrival of spring, work with an allergist to determine the sources of your allergies and the most effective treatment. Daily medication, nasal sprays, sinus rinses, and allergy shots are all possible ways to control allergy sensitivity and lessen the likelihood of an allergy attack. Managing allergies can help prevent sinus headaches, which can in turn help avoid a migraine trigger. In some cases, the variation in pollen and general allergen level is what triggers a migraine directly (which can be confused with a sinus headache). Controlling allergies may help in either case.