There is little evidence that weather triggers fibromyalgia pain and fatigue, according to a study published online in Arthritis Care & Research. Yet previous research has found up to 92 percent of people with the chronic condition say specific weather conditions affect their symptoms.

“Our study shows more evidence against – than in support of – an influence of specific weather conditions on daily symptoms of pain and fatigue,” explains lead study author Ercolie R. Bossema, PhD, a member of the Psychorheumatology Research Group at the Department of Clinical and Health Psychology at Utrecht University in the Netherlands.

The study analyzed symptom diaries of 333 women with fibromyalgia, who were on average 47 years old and had been diagnosed an average of two years prior. For a 28-day period, the women rated on a one to five scale their daily pain and fatigue levels, as well as other variables (such as sleep quality and physical activity level). Researchers then compared those diary entries to weather information to assess the influence of five factors – air temperature, hours of sunshine, precipitation, relative humidity and atmospheric pressure – on the symptoms.

The comparison failed to find consistent links. Of the 50 different analyses conducted, only 10 percent showed weather variables having a significant but small effect on symptoms. For example, one analysis found that an increase in temperature of 10 degrees Celsius (18 degrees Fahrenheit) caused average an increase in fatigue of 0.1 units (on a scale of one to five). Another found that each 1 percent increase in relative humidity was associated with a 0.004 unit increase in pain (on a scale of one to five).

“The pain and fatigue that patients report in diaries are not convincingly related to weather conditions,” Bossema says.

Researchers say their findings don’t rule out the possibility that some patients are more sensitive to weather than others. Twenty percent of the analyses showed small differences in the way patients reacted to changing weather. “Some patients experience somewhat more pain when air temperature is relatively high and other patients experience somewhat less pain when air temperature is relatively high, but for most of the patients such an association was not found,” Bossema explains.

Researchers also looked at other factors that might play a role in weather sensitivity, such as physical activity and depression, but found no evidence of a link there either.

Why do so many with fibromyalgia believe in a link? “Since there is always weather, and both the weather and symptoms change regularly, we hypothesize that it is easy to couple the two and hard to disprove such a link between the two,” Bossema says.

Carmen E. Gota, MD, director of the Fibromyalgia Clinic in the Orthopaedic & Rheumatologic Institute at the Cleveland Clinic in Ohio, says she believes this study reaffirms that fibromyalgia patients may have sensitivity to weather changes, but shows that it is not the major cause of their symptoms. “I think weather is a factor that affects pain and fatigue. But it’s not a major determinant. If someone has fibromyalgia they will have pain irrespective of weather. But if the weather is bad, they may be more aware of pain.”

Dr. Gota says it’s hard to argue that weather doesn’t affect some fibromyalgia patients, especially those who seem able to predict the weather based on their symptoms. “It has to be changes in barometric pressure or humidity that they are able to sense,” she says.

She also points to the fact that past research has shown a link between sunshine and depression; fibromyalgia and depression are strongly associated. “So it is possible that some weather changes that influence fibromyalgia symptoms are via the influence on mood,” she suggests.

Dr. Gota says her recommendation to fibromyalgia patients is: Make a point to enjoy the sunshine and good weather when it’s there and increase your exercise and activity level when the weather takes a turn for the worse. “One theory of why people feel better in good weather is they exercise more and are outside more and have more energy to do things,” she explains.

Although evidence of a connection between fibromyalgia symptoms and weather was weak, Bossema says that researchers will continue to look for factors that cause and impact the condition. In the meantime, she says, “I hope that people make the best of living with fibromyalgia independent of the weather. When having pain or fatigue, it is good to realize that sunshine comes after rain.