Short answer: there is no universal barometric-pressure threshold that predicts a migraine for every person. Compare the same pressure source with both headache and headache-free days.

Barometric pressure and migraine: what a diary can tell you

Some people report migraine attacks around weather changes. A pressure reading alone cannot tell you whether an attack will happen, and a diary can reveal an association without proving that pressure caused it.

Updated September 9, 2026 · Arve Tech, maker of DIM

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Is there a pressure threshold for migraine?

Do not treat a particular hPa value or daily drop as a universal trigger. Pressure, humidity, temperature and routines can change together. The Migraine Trust’s summer guidance discusses weather-related concerns, but it does not provide a validated personal attack forecast.

A website that labels tomorrow ‘high risk’ needs evidence for that prediction in the people using it. A weather forecast and a migraine forecast are different products.

Record the observation before drawing the conclusion

  1. Use one weather source and keep its location, timestamp and pressure unit with the entry.
  2. Record headache timing and changes in sleep, meals or routine separately.
  3. Include days without headache and mark missing records as unknown.
  4. Bring the pattern and its exceptions to your clinician.

A pressure change needs two comparable observations: ‘1008 hPa’ is a level; ‘1014 to 1008 hPa over 24 hours’ describes a change. Do not mix stations or sea-level-adjusted and station-pressure readings.

Worked example: the missing comparison

Imagine 10 days with a falling-pressure observation. Headache occurred on 3. On 10 other recorded days, headache also occurred on 3. Remembering only the three storm-day headaches would create a misleading impression.

This invented example illustrates the need for comparison days. Even a difference between the groups would not establish causation: the sample may be small and other conditions may differ. There is no guaranteed number of attacks after which a diary proves or rules out a trigger.

Use a weather log without changing your treatment

Start with the free weather and migraine log. You can enter your own observations, print the sheet or export CSV. The weather tool gives weather context, not a medical risk score. For heat and humidity, read the separate weather guide.

Keep following your agreed care plan. A pressure forecast is not a reason by itself to start, stop or change medication.

Editorial note: educational information from the maker of DIM; not an independent clinical review.

Dim is a diary, not a medical device. This article is general information, not medical advice — it does not diagnose, treat, or prevent any condition. Always consult a qualified clinician about your health.