With La Nina back for another summer and above average rainfall predicted for much of Australia, the weather is about to become more of a pain than people realise.

The notion of rain pain is often dismissed as a myth, but experts say there is now enough evidence to suggest it exists.

What's more, they say sufferers of conditions like arthritis and chronic pain can actually use their level of discomfort to tell when the weather is about to change.

La Nina was responsible for the Brisbane floods and Cyclone Yasi, and the Bureau of Meteorology says Queensland, New South Wales and Victoria in particular should brace for another wet summer.

Dr Graeme Jones, professor of rheumatology and epidemiology at the Menzies Research Institute, says the days of mythical rain pain are long gone.

He says arthritis sufferers' pain levels are without a doubt affected by the weather.

"There are three things in the weather that have an effect," he said.

"The higher the ambient temperature the better the symptoms are; the higher the humidity or dew point the worse the symptoms are; and changes in the barometric pressure, so when a cold front is coming through and when the pressure drops, people tend to ache in their joints before that."

He says their ability to predict the weather is not as farfetched as it sounds.

"My patients have been telling me they can predict the weather for 20 years, and most people were fairly disbelieving, when in fact the studies on the relationship between weather changes and pain are pretty consistent," he said.

"On an anecdotal level, last summer in Tasmania people's joints were much worse because we had a fairly wet winter and wet summer with lots of changes in the weather, whereas generally our summer is very dry."

Psychological factors

Conjoint Professor Nikolai Bogduk from the University of Newcastle, who specialises in spinal pain, is a little less convinced.

He says psychological factors may play a part.

"There is a theory, unproven, that when the barometric pressure drops the ambient pressure is lower and so joints expand, so if you have a painful knee it swells, and that's what makes it more painful," he said.

"That may or may not be true, but it is important for people to be alert to possible intermediate affects.

"Among them is the general affect of weather on people's mood. A patient without pain is going to feel more miserable when the weather is miserable, so a patient that is going to be affected psychologically may well be giving you an amplified measure of their pain on that particular day," he said.

"There may actually be no difference to the pain, but because they feel worse, they will report their pain as being worse."

In terms of pain sufferers' ability to predict the weather, Conjoint Professor Bogduk says a change in blood flow may be the explanation.

"The ability to predict the weather may be related to a number of things, maybe not exactly the joints swelling, but if the ambient pressure is dropping maybe things like veins and the venous drainage out of the joint or out of the bone changes, so there might be changes in blood flow that are occurring," he said.

No escape

Dr Jones jokes that it is difficult for people to avoid weather-inflicted pain in Australia.

"If you got sick of changes in the weather in Tasmania then you could move to Queensland where the high temperature will help your symptoms, but the high humidity won't," he said.

"So then you could move to Canberra, but the fog during winter could make you depressed and then that would make your pain worse."

ABC News Online asked people on Twitter what they thought.

"I have fibromyalgia and rheumatoid arthritis and I can say without doubt that rain does affect my pain," Wendy Fisher from Perth said.

"I have had chronic neck pain for six years. Yes, weather affects pain levels," Barry Steele from Sydney said.

"If it's been dry for a while I can feel big rain coming a week before the rain starts," Matthew Ross from the New South Wales central cost said.

"I have very accurate magic rain-detecting body parts. Some old injuries, some fibromyalgia," said Steph Bateman-Graham from Perth.

Others, however, were still sceptical.

"Rain pain?? - I've never heard of that particular term! Is it an ailment that actually exists? Sounds over the top to me!," Karen Hempel from Albury, in New South Wales, said.