The results of various studies have tended to reveal the following general pattern:
| Lower pressure is more commonly associated with Barometric Pressure Non-Migraine Headaches. |
| Higher pressure is more commonly associated with Barometric Pressure Migraine Headaches. |
However, it is also apparent that the degree of sensitivity and types of symptom resulting from any particular type of weather condition varies considerably between people. The following lists the outcome from several different studies which highlights the variation in conditions that triggered weather related headaches in their test subjects:
- Rising Pressure + Rising temperature.
- Approximately a 7.5% higher risk for each 5ºC increment in temperature + evidence of higher risk with lower barometric pressures.
- Falling Pressure + fluctuating or extreme temperatures + increasing humidity with thickening clouds.
- Low Pressure + high temperature + high humidity + overcast skies
Even though specific conditions trigger headaches in some people e.g. pressure or humidity readings above or below a certain figure, various studies have indicated that the most important factor for the majority of sufferers regarding weather related headaches and migraines, is the change in pressure over time (pressure tendency), temperature or humidity. For example:
A person believes they have more headaches in the summer when the weather is hot i.e. headaches are caused by high temperature and associated high pressure. However, through keeping a Headache Diary they find that their headaches do not occur when the weather is actually hot and stable. In fact, their headaches only occur when the weather enters a period of hotter weather i.e. headaches are caused by a sudden rise in barometric pressure which coincides with improving weather…it is the upward change in barometric pressure that causes their headaches.