I don't recall coming across heat as a commonly listed migraine trigger, but I'm suspecting it's the case with me. My worst migraines strike during the night and I wake up drenched in sweat, the temperature in my bedroom too high. (The heat in our house is inconsistent and unreliable, so not only is the upstairs much warmer than the downstairs, the temperature seems to fluctuate.) I sleep much better in a cool to cold room.
When I'm at work and in hot rooms, it seems like I tend to get more headaches, but I'm not as sure about that pattern, since I haven't been watching as closely at work.
Anyone else have heat as a trigger? Or know heat-induced migraine-like headaches to be symptomatic of something else?