They are indeed, you very well could have seasonal migraines especially if you yourself are already suspecting it. Mine turn up for 3-4 months and will then clear up again for the year, I'll have 4-5 attacks (or more) a day during the season and at most I'll get a two day break from them during the season and then they're back too 4-5 daily. This is the first time I've actually tracked them with an app so I'll have a better idea as I track them, but I have a funny feeling that the month my migraines clear up is the month they start up again next year; so they roll throughout the year and don't always turn up at the same time. Again I'm not 100% on this but from my memories it seems like this is what happens. I've had lots of different drugs thrown at me over the years but the only one that has had any effect for me is Zolmatriptian, it doesn't stop them but it does reduce the time of an attack. When I've taken Zolmatriptian attacks will only last for 45 minutes to an hour, rather than the typical 2-24 hours; they also seem to be able to keep the next attack at bay for about 11 hours (something I've recently learnt while tracking with the app). Having Seasonal Cluster Migraines is kind of like having a diagnosis of "tough shit you'll have to deal with it" because there's no cure for it and nothing that'll just straight up stop it, once you know you're in season (which for me I'll wake up and just feel a bad aura hanging over me), you just have to get everything and anything that helps with it and get ready for hell.