There are several migraine triggers that I know of when it comes to the weather. One of the big ones is atmospheric pressure change, which may affect the pressure on joints and sinuses. This is more common to the north and along the main jet stream flow, where we have larger storms, especially during the winter. Pressure changes also are linked to changing weather, just like we’ve had a little more than usual this summer. This could be why you had more migraines this summer compared to other summers. Pressure changes also cause wind, which can be a stress that sparks headaches. This, too, would be a little more common in the northern states.
There are other weather-related reasons for headaches that may not be relieved by moving south. Heat and humidity also can trigger migraines, as well as dehydration, which is linked to not only heat, but also elevation, a problem that may be enhanced in places in the western part of the country. Lastly, allergies may be an issue. A portion of this summer was very humid, a condition that increases mold spores. The southeastern part of the country would be worse for those suffering from mold-related allergies.
My biggest suggestion in a situation like this is to keep a log of your headaches along with a summary of the weather. That could tell you if there is a link to weather.