A Barometric Pressure Headache develops under certain barometric pressure conditions and can be either non-migraine type or migraine type.
Barometric Pressure Non-Migraine Headache Barometric Pressure Migraine Headache

Simple type headache of non-migraine origin that is caused or triggered by changes in barometric pressure. For symptoms refer to:
Barometric Pressure Headache Symptoms.

People who suffer from migraines (migraineurs) experience a distinct medical condition characterized by periodic, severe and debilitating headaches typically lasting 4-72 hrs (average 24 hrs) that are usually accompanied by nausea and altered bodily perceptions that interfere with the person’s ability to function during an attack. For symptoms refer to:
Barometric Pressure Headache Symptoms.

Most barometric pressure sensitive individuals experience this category of headache.

Headache statistics from various studies reveal: 
12% of the general population suffer migraine headaches. 
Over 50% of migraine sufferers (migraineurs) are sensitive to weather conditions.
Weather conditions (including barometric pressure) are considered to be the 2nd or 3rd most common migraine trigger.

The sensitivity to and degree of pain experienced from changes in barometric pressure, varies considerably between people in this category.

Migraines can be initiated by various triggers of which changing barometric pressure may be just one example.

Other interacting factors such as underlying medical conditions or the degree of stress, tension, amount or overuse of drugs e.g caffeine, nicotine, alcohol may also influence the headache. In general, migraines are more common amongst women (hormonal changes are a factor), tend to run in families and typically occur 1 to 2 times per month.
Pressing pain sensations akin to Tension-Type Headaches may develop associated with the face, upper neck , scalp and head. Migraine headaches are the principal form of vascular headaches i.e. pain resulting from swelling and stretching of blood vessels in the head. There is growing evidence to indicate that other changes take place within the brain during a migraine aside from just vascular fluctuations.
Barometric Pressure Non-Migraine Headaches are frequently associated with lower barometric pressure conditions. If a migraineur is barometric pressure sensitive, their migraines are often associated with conditions involving higher barometric pressure, especially in combination with elevated temperatures