The 6 Migraine Triggers You Can Actually Measure

Most migraine advice you have read is unmeasurable. "Reduce stress." "Stay hydrated." "Watch your sleep." Sure. You have been doing that for years and your head still throbs on Tuesdays for reasons nobody can name. What if, instead of fuzzy guidance about lifestyle, you could open your phone before brushing your teeth and look at six actual numbers — six variables, all of them free, all of them updated within the last hour, all of them plausibly tied to whether today is going to be one of the bad ones?

That is what this article is about. Not twelve tips. Not a holistic protocol. Six numbers, ranked roughly by how much actual research backs them, with thresholds you can decide to care about and live links to where the data lives.

If you are looking for a clean answer about which one matters most for you specifically — that answer is not in this article, it is in three weeks of your own diary. But you will know where to look.

1. Barometric pressure change rate

Not the absolute number. The rate. This distinction trips up almost every weather app on the market, and it is the single most important thing you can learn from this whole post.

If the pressure is steady at 998 hPa for three days, your trigeminal nerve is mostly fine with that. It is the transition that hurts. A 6-hectopascal drop across three hours, the kind that announces an incoming front, is roughly equivalent (in terms of pressure differential per unit time) to an elevator ride from sea level halfway up a small mountain. Your sinuses, your inner ear, and apparently your trigeminal nerve all notice.

The 2019 narrative review by Maini and Schuster in Current Pain and Headache Reports (PMID 31707623) walked through the barometric-headache literature and found exactly the messy result you would expect — multiple studies, partial reproducibility, and a clear subgroup of patients for whom the effect is real and persistent. The Maini-Schuster takeaway, the one nobody quotes, is that mean pressure values do almost nothing predictive. Change rate does the work.

Threshold to care about: a fall of 6 hPa or more across 3 hours, or 10 hPa or more across 12 hours. Below that, most sensitive people are fine. Above it, prepare.

Where to check it: any decent weather service shows a pressure trend. For a single live wellness number that already factors in barometric movement across 32 cities, check the live score — it folds pressure delta into the overall reading.

2. The geomagnetic Kp index

The Kp index is a 0–9 number that measures global geomagnetic disturbance, updated every three hours by the NOAA Space Weather Prediction Center. When the Sun belches a coronal mass ejection at us and the solar wind disturbs Earth's magnetosphere, Kp climbs. A boring day is Kp 1 or 2. A noticeable disturbance is Kp 4. A geomagnetic storm starts at Kp 5. Severe storm conditions reach Kp 7 or higher.

Why would a number about charged particles in space matter for the inside of your skull? Honestly, the mechanism is not nailed down. The leading hypothesis points at melatonin disruption — the pineal gland is sensitive to magnetic field variation in animal studies, and melatonin is one of the cleaner threads connecting circadian rhythm to migraine onset. Other researchers point at nitric oxide pathways, others at trigeminovascular reactivity. Nobody has won that argument yet. What is clearer is the population correlation: in self-reported diary studies, geomagnetically active days show modestly elevated migraine rates compared to quiet days, and a self-aware subgroup of patients can predict their attacks from Kp better than chance.

Threshold to care about: Kp ≥ 5 (the storm threshold). At Kp ≥ 6, people who track this carefully often plan their day around it.

Where to check it: the NOAA SWPC 3-day forecast page (swpc.noaa.gov) is the official source. The same value flows into the live score automatically, so you do not have to read SWPC every morning unless you enjoy it.

3. Schumann resonance amplitude

This is the strangest of the six and I will be honest about it.

The Earth has a standing electromagnetic wave between its surface and the ionosphere, oscillating at roughly 7.83 Hz with weaker harmonics at 14, 20, 26, and 32 Hz. The Schumann resonance, named after the German physicist Winfried Otto Schumann who predicted it in 1952, is real, well-measured, and not woo. Its amplitude rises and falls with global lightning activity and with solar weather, and it can spike sharply during geomagnetic storms.

Whether it affects human physiology in any measurable way is a different question, and the mainstream neurology consensus is currently a polite shrug. There are small studies suggesting EEG and heart rate variability respond to Schumann variations under controlled conditions. There are zero large randomized trials. The American Migraine Foundation does not list Schumann amplitude as a recognized trigger. So why is it in this article?

Because for a small, vocal subset of migraine sufferers, the correlation between Schumann amplitude spikes and their attack pattern is undeniable in their own diaries. And because, unlike the other woo-adjacent claims out there, this one is measurable in real time from three independent ground stations across the world. If the variable does nothing, your three-week diary will show no correlation and you can ignore it. If it does something, you will see it.

Threshold to care about: there is no consensus number. What matters is deviation from the recent baseline — if amplitude is sharply above the trailing 7-day average, that is the interesting moment.

Where to check it: sungeo.net pulls live spectrograms from three Schumann observatories. Take a look at Tomsk in Siberia, ETNA on Sicily, and Cumiana near Turin. Three stations because no single observatory should be the global truth.

4. Temperature swing across 24 hours

The 2024 narrative review by Denney, Lee, and Joshi in Current Pain and Headache Reports (PMID 38358443), titled "Whether Weather Matters with Migraine," surveyed the broader weather-trigger literature and found that across studies, weather variables collectively account for roughly a fifth of self-reported migraine triggers. Inside that bucket, temperature change kept showing up — not absolute hot or cold, but the swing. Especially the evening-to-morning swing.

A 10°C drop overnight, the kind that announces a cold front in spring or autumn, correlates with elevated next-morning migraine onset in several diary studies. Why? Probably the same broad family of vasoreactive mechanisms that govern the pressure response — when your peripheral vessels constrict and dilate to handle thermal regulation, the trigeminal nerve gets pulled along for the ride. Add a barometric front to the same morning (cold fronts and pressure drops travel together) and you have a compound trigger that reads in your diary as "yesterday was fine, today I am wrecked."

Threshold to care about: 8°C or more difference between today's low and yesterday's low. A 10°C swing is a stronger flag.

Where to check it: any weather service. The local met office of your country (DWD if you are in Germany, IMGW in Poland, NOAA NWS in the US, Météo-France in France) publishes hourly history. Look at the temperature curve, not the forecast.

5. Relative humidity shift

This one is less famous than pressure but it shows up consistently in patient diaries, especially among people who also have allergic rhinitis or sinus involvement. A sudden cross from dry air (below 40% RH) into humid air (above 70% RH) within twelve hours, or the reverse, correlates with migraine onset in a subset of weather-sensitive patients.

The mechanism is debated. Mucous-membrane swelling in the sinuses changes pressure dynamics inside the head. Hydration status of the nasal mucosa changes how the trigeminal afferents fire. Some researchers also connect humidity shifts to airborne mold spore counts, which is a different chain of causation entirely. The effect, where it exists, is smaller than barometric pressure or Kp, but it is real for some people.

If you tend to migraine on the day after a thunderstorm has cleared, when the air goes from saturated to suddenly dry — that is humidity shift, not pressure rebound. Worth tracking.

Threshold to care about: a 30% or greater RH change in either direction within 12 hours.

Where to check it: same place as temperature, your local met office. Most weather apps show RH in the hourly view, you just have to scroll past the temperature to find it.

6. The moon phase window

Here is where I have to be honest with you, because if I weren't, this whole article would lose its credibility.

The evidence for a lunar effect on migraine is thin. Multiple small studies have looked, multiple have found nothing, and the few that found a weak signal are not strongly reproducible. The mechanism, if there is one, is contested — proposed routes include tidal-gravitational variation (very small), light exposure during full moon (modest, maybe relevant for circadian-sensitive people), and psychological priming where you notice the moon and then notice your headache. The American Migraine Foundation does not list lunar cycle as a recognized trigger.

So why include it as the sixth? Two reasons.

First, because some patients report a stable pattern across years of careful diary-keeping, and at the level of personal pattern-tracking, that is data even if it does not aggregate. Second, because the moon phase is trivially measurable — no app, no website, just look up — and including a measurable variable that might do nothing is a more honest list than excluding it because the meta-analyses are unimpressive.

If you turn out to be a person whose migraines cluster around the full moon ±2 days, after three weeks of diary tracking, that is your real pattern. If you do not, you will know after three weeks and can stop checking.

Threshold to care about: full moon ±2 days, new moon ±2 days. Five days a month total, roughly one in six.

Where to check it: any calendar. Or any astronomy app. Or look up.

What to do with these six

The real value of this list is not memorising the thresholds. It is building a 21-day diary against actual numbers, not vibes.

Pick three of the six to start. Maybe pressure change, Kp, and temperature swing — the three with the most research backing. Each morning when you wake, write down the date, the score from today's reading, and how your head feels on a 0-3 scale. Twenty-one mornings. After three weeks, you will know more about which numbers track your specific neurology than any generic guide could ever tell you. If pressure change correlates and Kp does not, you have learned something. If both correlate, you have learned more. If neither does, you have learned that for you, the trigger lives somewhere else — diet, sleep, hormones — and you can stop scanning the sky.

The point of the headache forecast is to make this measurement effort almost free. You do not have to read NOAA, the local met office, and three Schumann spectrograms before coffee. Someone else has done that. You just glance at the number.

You probably already know one or two of your triggers from years of painful learning. The reason this list of six exists is that the others — the ones you did not catch because you were not looking at the right variable — might be hiding in plain sight. Tomorrow morning, before the next migraine writes itself across your day, you can look.