Most people treat Austin's summer heat as a seasonal inconvenience — drink an extra glass of water, move the workout to 6 a.m., get on with the day. For people managing high blood pressure, migraines, thyroid disorders, or cardiovascular disease, the calculus is more complicated. Austin summers don't just make those conditions uncomfortable. Under the right circumstances, they make them worse in ways that can go unnoticed until the damage is already done.