Can Rain Affect Joint Pain?

Working as an osteopath in the UK, it’s not unusual to hear patients say that their joints are worse when it rains. Some are absolutely convinced they can tell when the weather is about to change because an arthritic knee starts aching or an old injury suddenly becomes more noticeable.

With the amount of rain we get here, it’s an interesting one. Is there actually something happening within our joints when the weather changes, or have we just become very good at blaming the British weather?

There has actually been quite a bit of research into it, although interestingly, the rain itself probably isn’t the important part.

Changes in atmospheric pressure

Most research has looked at barometric pressure and temperature rather than rainfall.

Barometric pressure is simply the pressure of the atmosphere around us, and it changes as different weather systems move through. Those changes often happen alongside the wet and unsettled weather we are very familiar with in the UK.

One study followed 205 people with knee osteoarthritis and found that changes in barometric pressure were associated with changes in their pain. Colder temperatures were also linked with increased pain.

The researchers found that for every one inch of mercury change in barometric pressure, knee pain scores increased by around one point.

So when a patient tells me they can “feel the rain coming”, I wouldn't necessarily dismiss it. They may not be responding to the rain at all, but to some of the atmospheric changes happening around the same time.

But how could the weather affect a joint?

Pressure within our joints normally sits slightly below the atmospheric pressure around us. This has led to the theory that when atmospheric pressure changes, tissues within and around the joint may respond to that change too.

If a joint is healthy and comfortable, we probably wouldn't notice such a small difference. But could an arthritic, inflamed or previously injured joint be more sensitive to it?

There is biological reasoning behind the idea, but we don't yet have enough evidence to say this is definitely what is happening.

Cold weather may be important too

Does temperature play a role? Anyone with a stiff knee, hip or back will probably recognise that getting moving on a warm summer morning can feel quite different to getting out of bed on a cold January morning.

Synovial fluid, which helps lubricate our joints, can become more viscous at lower temperatures, which is one possible explanation for increased stiffness.

Another, much simpler explanation that I think is particularly relevant in the UK. When it is cold, dark and pouring with rain, we move less.

The dog walk becomes shorter. We drive somewhere we might normally walk. Gardening stops. We spend more time sitting indoors and generally become less active.

For somebody with osteoarthritis or an already painful joint, that reduction in movement can make quite a difference. Joints tend to like regular movement, and prolonged periods of inactivity can increase stiffness and discomfort.

So some of the pain we associate with rainy weather could actually be related to what we do differently because it is raining.

The evidence isn't completely convincing

Although there are studies showing associations between weather and joint pain, the overall research is mixed.

A systematic review looking at 16 studies found no clear consensus. Other reviews have found that many studies do report some relationship, but they don't necessarily agree on what part of the weather matters. Some point towards temperature, some atmospheric pressure, others humidity.

There is also the issue of expectation; if you already believe your knee hurts when it rains, you're much more likely to remember the particularly wet day when your knee was awful than the wet day when it didn't bother you at all. Researchers have previously raised this selective recall as one reason the relationship between weather and arthritis is so difficult to untangle.

That doesn't mean patients aren't experiencing something real. It just means there are probably several things going on rather than one simple explanation.

So, can rain make your joints hurt?

The most accurate answer at the moment is: perhaps indirectly, and for some people more than others.

There is enough evidence around temperature and atmospheric pressure to make the association plausible, particularly in people with osteoarthritis or sensitive joints. But we can't confidently say that rain itself causes joint pain.

What we do know is that cold, wet weather often means less movement, more time indoors and more stiffness. Those are things we can actually do something about.

If you know your joints tend to complain when the weather changes, try not to let several wet days become several inactive days. Keep walking where you can, move your joints regularly and continue with any strengthening or mobility exercises you've been given.

And if you really can predict tomorrow's rain from your knee, the research hasn't quite proved this right or wrong.

References

McAlindon TE, Formica M, Schmid CH, Fletcher J. Changes in barometric pressure and ambient temperature influence osteoarthritis pain. The American Journal of Medicine. 2007;120(5):429–434.

Redelmeier DA, Tversky A. On the belief that arthritis pain is related to the weather. Proceedings of the National Academy of Sciences. 1996;93(7):2895–2896.

Arthritis Foundation. Best Climate for Arthritis Patients: Humidity's Impact on Your Joints.