I get this kind of migraine and they sometimes come in "clumps" - often if I experience a climate change or there is change of light.. but also will occur in isolated incidents. I mark my diary with an M for this and M/H if I get a significant headache too. Even though I have done this for a couple of years cant see a pattern although sometimes can trace a trigger for the isolated ones eg light or diet.
I had few migraines during livelier part of my existence but get them more frequently now I am older. My two daughters both had migraines when younger but now in twenties get them less. There is a hormonal component it seems as well as heredity factor.
I dont take medication except pain killers for headache but have made significant changes to diet. My eldest daughter had food allergy tests as her migraines were ferocious when a child and by following a diet regime she was heaps better. I use a similar but not as strict diet now so avoid gluten and am cautious with amine foods as well as restricting, not totally eliminating, dairy.

All the best, this is such an enervating disease as I find after migraine gone I am shot for the rest of that day.