[Gatsky]

Barometric pressure is thought to induce headaches in some people [1]. Another possibility could be allergens, particularly grass pollen and tree pollen which can display large geographic variations. Another is ergonomics, eg are you using a laptop in some places and not others, or is your set up less ergonomic in some places.

I must say this pattern of headache is a bit unusual. Migraines shouldn't persist for months, and they are the typical type of headache induced by barometric pressure. If you have the means then think about getting an MRI brain. Very rarely there could be something like a vascular malformation which would be worth discovering. There is a risk of unrelated incidental findings however.

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4684554/