The fact that weather has an effect on how arthritis is felt by its sufferers is well documented, with surveys showing as many as 93% of arthritis sufferers believing that weather affects their pain level, and 68% believing that weather severely affects their pain level. Patients with arthritis often claim they can predict the weather, based upon their pain level, and a number of studies have been conducted to test this hypothesis. While these studies show that the effects of weather can vary from person to person, many show that arthritis pain is increased by a variety of weather factors, which may swell inflamed arthritic joints, stretching the inflamed joint lining and capsule, thereby increasing the pain of arthritis.

Among the types of weather that may increase joint sensitivity and arthritic pain are:

1. Changes in atmospheric pressure, especially falling pressure
2. Changes in temperature, especially lowering temperature
3. High or increasing relative or absolute humidity
4. Relatively low atmospheric pressure
5. Low temperatures
6. Precipitation

Arthritic pain can be especially severe when these conditions are combined, such as during chilly, damp weather when pressure is low and falling.

Now, AccuWeather has developed an index that combines all of the weather factors that may affect arthritis sufferers, and summarizes the most likely severity of weather-related arthritis pain in one easy-to-understand scale, from Low to Extreme. Available exclusively on AccuWeather.com, the AccuWeather Arthritis Index forecasts this level for each of the next several days, so arthritis sufferers can have advanced notice of when they are most likely to have increased pain, allowing them to take appropriate medication and to better plan activities.