Background and Concept

You've probably heard someone say,
“My knee hurts—rain must be coming.”
Especially among elderly people, this idea is widespread.
But is there scientific truth behind this belief?

Is There a Scientific Basis?

Yes, somewhat. Many studies suggest a connection between barometric pressure and joint pain.
Before it rains, atmospheric pressure drops,
which can affect joint tissues, especially in those with arthritis or past injuries.

• Low pressure → tissue expansion in joints → pain signals

• Especially affects people with arthritis or joint surgeries

So while it's not a forecast, it's not just superstition either.

What’s the Accuracy?

Although it can’t predict rain like a weather app, statistics show:

• About 60–70% of arthritis patients report increased pain with weather changes

• Some studies suggest pain-based “predictions” are accurate about 50% of the time

So it’s better than random, but not reliable enough to ditch the umbrella app.

Interesting Facts

• People with metal implants also report increased weather-related discomfort

• Japan even has a term for it: “tenki-tsuu” (weather pain)

• Studies in Canada and Germany show similar reports

Summary

Sources

• Journal of Rheumatology, 2021

• Harvard Health Publishing

• Japan Weather Pain Institute Report, 2020

Tags

joint pain, knee ache, weather prediction, barometric pressure, rain signs, weather-related pain