"Rain's coming, my knee can tell." If you live with arthritis or an old injury, you may have said this yourself. Plenty of people are certain that weather affects joint pain, and the research still gives no single answer.
You do not have to pick a side in that debate. Four weeks of careful records let you test the question on your own data, set up so that memory and expectation distort the result as little as possible.
What the research shows so far
The findings point in different directions, and three studies show why:
- A small link. The University of Manchester's "Cloudy with a Chance of Pain" project matched daily pain ratings from a smartphone app with local weather data for participants across the UK. The analysis, published in 2019, found slightly higher pain on humid, windy days with low air pressure. The effect was small.
- No link with rain. Researchers at Harvard Medical School analysed insurance claims from older Americans (British Medical Journal, 2017). They found no link between rainy days and doctor visits for joint or back pain. Doctor visits are not the same as pain levels, though.
- Belief without a signal. In 1996 the physician Donald Redelmeier and the psychologist Amos Tversky followed people with rheumatoid arthritis for many months. Most were convinced their pain tracked the weather. The two researchers found no such pattern in their measurements.
Researchers discuss changes in air pressure that might affect tissue in and around irritated joints, and cold that makes muscles and joints stiffer. Your behaviour plays a part as well: on a grey, wet day you move less and sit more. A weak effect in some people is possible. In your case it could be larger, smaller or zero.
Why your memory makes a poor instrument
A bad day during a storm sticks in your mind because it fits what you expected. A bad day in sunshine fades, and so does the rainy day when your knee stayed quiet. After a few months you only count the hits.
Expectation also works in the moment. If you checked the forecast in the morning and know a low is coming, you read a slight ache as a sign more readily. Then there are factors that change with the weather: less movement, more time on the sofa, poorer sleep in the heat. Without records you cannot separate these from air pressure.
The four-week self-test
Before you start
- Write your hunch down in specific terms. For example: "On days when the weather changes, my right knee averages at least 1 point higher." Set the threshold in advance so you cannot adjust it afterwards.
- Pick one weather factor and one source. Choose the one you suspect: a change in the weather, falling pressure, cold and damp, or a heatwave. The National Weather Service, the Met Office or your phone's weather app will do. Use the same source for all four weeks.
Every day
- Log your pain at the same time each day, good days included. Number first, weather second.
- Record the weather separately from your source, as a yes or no: did your weather factor occur today?
- Note the confounders: movement, long periods of sitting, sleep.
After four weeks
Split the days into two groups and average each one. A made-up example:
| Days | Average pain | |
|---|---|---|
| weather changed | 7 | 5.1 |
| no change | 21 | 4.3 |
- Check the numbers behind it. With only two or three weather days, a difference means little; extend the test to eight weeks. Look at the day before each change as well, in case you believe you feel the weather coming.
- Compare with your threshold. If the gap disappears once you remove the days you sat for hours, the sitting explains more than the weather.
For the curious, there is an extra forecast test. Each evening, before you look at a weather app, write down whether your joint expects a change tomorrow. After four weeks, set your notes beside your source's data. If you score hardly better than a coin toss, you probably do not feel the weather in advance.
A joint that suddenly swells, turns red and feels hot needs prompt medical attention, especially with a fever, whatever the weather is doing.
How to run the test in PainTrack
PainTrack does not fetch weather data, so you set the weather tag yourself. Under "+ Add tags" there is a built-in tag, "weather changed". For a more specific hunch, create your own tag under More → Tags, such as "pressure falling" or "cold and damp". For the confounders, "was moving around", "sat for a long time" and "slept poorly" are already there.
Entries, tags and the History chart for 7 and 30 days are free, and you can count the two groups yourself in the Diary. With Pro, the trigger analysis on the Analysis page does the comparison for you: it sets your intensity on entries with a tag against entries without it, over the last 180 days. A tag appears once there are 12 entries, at least 4 with it and 4 without. Differences under 0.5 points show in grey as "no clear difference", and every result carries the note "A correlation, not a cause". Pro also extends the History chart to 90 days and all time.
To look for triggers beyond the weather, read finding your pain triggers. For joints in particular, see tracking arthritis joint pain, and the basics are in the guide to keeping a pain diary.
Frequently asked questions
Is there scientific evidence that weather affects joint pain? Partly. Some studies find a small link with humidity, wind and low air pressure, others find none. A strong effect that applies to everyone has not been shown.
Why do my joints hurt when the weather changes? Nobody has settled that yet. Researchers discuss changes in air pressure, cold, and the way you behave on bad-weather days, such as moving less.
How long should I keep a weather and pain diary? Four weeks is a good start. If your weather factor turned up on only a few days, extend to eight weeks so both groups have enough days.
Can an app detect the link with weather automatically? PainTrack does not pull in weather data. You set the weather tag yourself, and the trigger analysis (Pro) then compares your values with and without it.
PainTrack is not a medical device and does not replace medical diagnosis or treatment. The app is intended for personal documentation and self-observation.