Weather changes may trigger migraine headaches, but there is no evidence sufferers can use their pain to predict the weather, according to a study released on Thursday.

The study, presented the annual meeting of the American Headache Society in Vancouver, found that 51 percent of the migraine sufferers studied were sensitive to changes in the weather, such as temperature and barometric pressure.

“Most people in the study thought they could predict which type of weather factor triggered their migraines, but they really couldn’t,” researcher Marcelo Bigal of the New England Center for Headache said in a statement.

The study compared the personal headache records of 77 migraine sufferers over two years with data collected by the U.S. National Weather Service.

Temperature or humidity changes sparked pain in 34 percent of sufferers, while 14 percent were hit when a weather pattern changed and 13 percent when it was a pressure change. About 10 percent had their pain triggered by more than one type of weather change.