Why do headaches and old injuries flare up before it rains?
― Your body can sense a pressure change equal to climbing dozens of floors
"My knee aches when rain is coming." "My head feels heavy before a typhoon." This old saying might not be just imagination. As a low-pressure system approaches, the air around us gets as light as it would at the top of a tall building. Our inner ear is thought to sense that small change.
You wake up feeling a bit heavy-headed. Your temples throb. It's still clear outside, but the forecast says "rain from this afternoon."
Someone in your family says, "That ankle I hurt years ago is aching again." Even before the rain starts, the body seems to notice first.
Nothing in the sky has changed yet — so what is the body actually sensing?
There are two reasons the body "knows" before it rains
As a low-pressure system approaches, the air presses down less from above. Even an ordinary low can bring about the same change as climbing a building nearly 100 metres tall.
Deep in the ear sits an organ that senses tilt and rotation. It's thought to also respond to pressure changes, unsettling the nerves that keep the body's condition in balance.
Headaches, dizziness and old-injury pain triggered by weather shifts are called "weather pain" or "meteoropathy." Let's look at each piece in turn.
A low-pressure system does to you what climbing a building does
We live at the bottom of an air column stacked kilometres high above our heads. The force from that weight pressing down is "air pressure." At ground level, it's normally around 1013 hectopascals.
Climb higher, and there's less air above you, so pressure drops. Near the ground, it falls by about 1 hectopascal for every 8–9 metres you climb.
Meanwhile, when a low-pressure system approaches, pressure drops just because you're in that location. Even an ordinary low can easily drop pressure by 10–20 hectopascals in a single day. A strong typhoon passing directly overhead can drop it by more than 50 hectopascals.
Try moving the slider in Figure 1. A 10-hectopascal drop equals climbing roughly an 85-metre building. For a strong typhoon, it's close to climbing higher than Tokyo Tower.
But here's a puzzle. Riding an elevator up ten floors drops pressure by 3–4 hectopascals in a few dozen seconds — far faster than any low-pressure system. Yet almost nobody gets a headache from an elevator ride.
So weather pain seems linked not to a "fast change" in pressure, but to a "slow change" unfolding over many hours. That's the heart of the mystery.
A sensor deep in the ear unsettles the body's balance
Deep inside the ear is a region called the "inner ear." Next to the organ that senses sound sit organs that sense tilt and rotation — the same ones blamed when "your eyes and ears disagree" during motion sickness.
Japanese researchers placed rats with chronic pain into a chamber where air pressure could be lowered, and studied them. Lowering the pressure increased pain responses — but not in rats whose inner ears had been damaged. This suggests the inner ear may be the entry point for sensing pressure change.
Signals from the inner ear also reach the brain's "autonomic nervous system," which automatically regulates heart rate and blood vessel width. When this nervous balance is disturbed, blood vessels widen and the head throbs, or pain intensifies in places already weakened (Figure 2).
There are other theories for why old injuries ache too. One holds that tissue around a past injury swells slightly more easily with surrounding pressure changes. Rather than any single cause, several factors may be combining at once.
In the UK, a study had over 10,000 people with chronic pain log their daily pain levels via smartphone. It found a slight tendency for pain to increase on days with high humidity, low pressure, and strong wind. The link with temperature was reportedly unclear.
So what should you do?
If you're prone to weather pain, watching the forecast's pressure trends can help you prepare mentally. Resting early and getting enough sleep are recommended ways to steady the autonomic nervous system. Some also suggest warming the area around the ears helps.
That said, never blame the weather for an unusually severe headache or one that strikes suddenly and intensely. Don't hesitate — consult a doctor.
Summary
As a low-pressure system approaches, just being in that location drops air pressure by as much as climbing a building dozens of floors tall. An organ deep in the ear is thought to sense this slow change, unsettling the autonomic nervous system and intensifying headaches and old-injury pain.
Aching before the rain might not be just imagination.
Deep in your ear, your body is listening to the air growing slightly lighter.
We cover the ear and pressure further in "Why do your ears hurt before a plane lands?," and the inner ear's role in "Why does motion make you sick?."
- If your smartphone has a barometer, open an app that shows the current pressure reading. Ride an elevator up and down a few floors and watch the number move.
- Record the pressure at the same spot every morning and evening. When a low-pressure system approaches, you'll see days where it drops by 10 hectopascals or more in a single day.
- On the same days, note how your head and body feel on a "good / normal / bad" scale. Keep this up for two to three weeks and compare it against your pressure graph.
Once you know which kind of weather your body is sensitive to, you can plan to rest in advance. Even without a barometer, you can keep the same log using the pressure figures from the forecast.
Want to know more? ― Terms, formulas, and how this connects to the curriculumWe mark which level each part belongs to, from middle-school science to university specialist courses
- Middle schoolCovered in middle-school science
- High schoolCovered in high-school "Basic Physics / Basic Earth Science / Basic Biology"
- High school+Advanced high-school content, or textbook sidebar material
- UniversityNot covered in high school — university specialist subjects (meteorology, neurophysiology)
- ResearchNot yet settled "textbook fact" even at university — something researchers are actively studying
Middle schoolTerms: this phenomenon has a name
- Air pressure (atmospheric pressure): the force from the weight of the air above your head. Measured in hectopascals; roughly 1013 hPa at ground level.
- Weather pain / meteoropathy: headaches, dizziness, joint pain and similar symptoms that appear or worsen with weather changes. Not a formal diagnosis — a name for a cluster of symptoms.
- Inner ear and autonomic nerves: the inner ear is the organ deep in the ear that senses sound and the body's tilt and rotation. Autonomic nerves regulate things like heart rate and blood vessel width without conscious control.
Middle schoolHigh schoolCheck it with a formula: how many metres does a low's pressure drop equal?
Let's calculate "how many metres of climbing" the pressure drop from a low would equal, if it stayed in one place. We consider the weight of the air layer near the ground.
| In symbols | Δp ＝ ρ × g × h (so h ＝ Δp ÷ ( ρ × g )) |
| In words | Pressure difference ＝ air density × gravitational acceleration × height difference |
| Where it comes from | The weight of an air layer of thickness h balances the pressure difference between its top and bottom (hydrostatic equilibrium) — the same formula behind water pressure increasing with depth |
| Air density near the ground ρ | about 1.2 kg/m³ (kilograms per cubic metre) |
| Gravitational acceleration g | 9.8 m/s² |
| Pressure drop for an ordinary low Δp | 10 hPa ＝ 1000 pascals |
| Pressure drop for a strong typhoon | 50 hPa ＝ 5000 pascals |
| Pressure difference per metre (ρ × g) | 1.2 × 9.8 ＝ 11.76 pascals |
| Height for an ordinary low (10 hPa) | 1000 ÷ 11.76 ≒ 85 m |
| Height for a strong typhoon (50 hPa) | 5000 ÷ 11.76 ≒ 425 m |
| Pressure difference from a 30 m elevator ride | 11.76 × 30 ≒ 353 pascals |
| Rate of change in the elevator (30 seconds, per second) | 353 ÷ 30 ≒ 11.8 pascals |
| Rate of change for a low (10 hPa over 1 day ＝ 86400 s, per second) | 1000 ÷ 86400 ≒ 0.0116 pascals |
| Ratio of rates (elevator ÷ low) | 11.8 ÷ 0.0116 ≒ 1017 |
An ordinary low equals climbing about 85 m; a strong typhoon equals about 425 m — higher than Tokyo Tower. Yet the rate of change is roughly 1000 times faster in an elevator. Since elevators don't trigger weather pain, the body seems to respond to a "slow, sustained change" instead. The effect of thinning air at altitude is only a few percent over this range, so it's negligible for our purposes.
High schoolHigh school+Why does pressure drop with height, and what does the inner ear sense?
High schoolAir pressure is determined by the weight of the air column above a given point. Climb higher, and that column gets shorter, so pressure drops. In Basic Earth Science, you learn that air flows inward toward the centre of a low, rising and forming clouds — this is why "a low brings rain."
High school+Inside the inner ear is a fluid called lymph. Tilt and rotation are detected when hair cells sense this fluid moving. The inner-ear hypothesis holds that pressure changes slightly affect this fluid or its surrounding membranes, generating a signal that's sent to the brain.
UniversityHydrostatic equilibrium, and the path from the vestibular system to the autonomic nerves
The formula above is exactly the hydrostatic equilibrium equation for the atmosphere. Accounting for air density itself decreasing with height gives the barometric formula, under which pressure falls exponentially with altitude. On the physiological side, signals reaching the brainstem's vestibular nuclei from the inner ear's vestibular organs are thought to influence the centres of the autonomic nervous system. The broader category of weather-triggered symptoms is called meteoropathy, studied in connection with migraines, joint pain, and dizziness.
📖 For the derivation and further reading: Hydrostatic equilibrium (Wikipedia, Japanese) ／ Meteoropathy (Wikipedia, Japanese)
ResearchWhat's still unclear
- Why does the body respond to "slow" change? Elevators produce a much faster change, yet don't trigger weather pain. Whether it's the size, speed, or duration of the change that matters is still unknown.
- Where in the inner ear, and how, is pressure sensed? Animal studies show the inner ear is involved, but which cells in the human inner ear actually pick up pressure change isn't clear.
- Where do individual differences come from? Some people feel the same weather strongly; others not at all. Human studies have produced mixed results, with some finding a link and others not.
In short, everything in this article is "the best explanation we have so far." Weather pain is a topic where an old folk belief is, bit by bit, being tested by science.
How this connects to the curriculum (by level)
| Level | Subject/Unit | Where in this article |
|---|---|---|
| Middle school | Science Year 2, "Weather and its changes" (atmospheric pressure, lows) | Pressure as the weight of air; pressure drops with a low |
| High school | Basic Physics "Pressure," Basic Earth Science "Structure of the atmosphere," Basic Biology "Autonomic nerves" | Checking it with a formula; the inner ear and autonomic nerves |
| High school+ | Biology "Receptors (equilibrium receptors)" | Inner-ear lymph fluid and hair cells |
| University | Meteorology (hydrostatic equilibrium, barometric formula), Neurophysiology (vestibular system, autonomic nervous system) | The university section |
| Research | Meteoromedicine, pain research | Response to slow change; individual differences |
| ― | Everyday connections | Watching pressure forecasts; resting early; keeping a symptom log |
- Dixon WG et al., "How the weather affects the pain of citizen scientists using a smartphone app," npj Digital Medicine (2019)
- Sato Jun et al., report of animal experiments examining how pressure drops intensify pain responses and the involvement of the inner ear (Nagoya University Environmental Medicine Research Institute, Aichi Medical University, and others)
- Meteoropathy (気象病) ― Wikipedia (Japanese)
- Hydrostatic equilibrium (静水圧平衡) ― Wikipedia (Japanese)
- Japan Meteorological Agency, explanations of "air pressure" and "low-pressure systems" (JMA website, "Knowledge & Explanations")
※This article is a general-audience science explainer. The figures given are approximations meant to aid understanding, not precise values. How symptoms are felt varies greatly between individuals. If you have an unusually severe or persistent headache, please consult a medical professional.