Central Florida is famously one of the most lightning-prone places in the country, and from June into September the Lake Mary area gets its rain the local way: a towering afternoon thunderstorm, an hour of violence, then steam. Your chimney, masonry or chase, is the tallest, most exposed thing on the house, and it takes those storms head-on all summer long. Wind-driven rain finds gaps that vertical rain never tests, and a summer's worth of daily soakings will exploit any weakness at the top of the stack.
On masonry chimneys, the usual entry points are a hairline-cracked crown, tired flashing where the chimney meets the roof, and bare brick that simply drinks water. On chase systems, it's the cover seams and the siding joints. Either way, the leak rarely shows up at the chimney itself. It appears as a ceiling stain a few feet away, a peeling corner of paint, or a musty smell in a room you don't use. Real chimney leak repair starts with finding the actual entry point, because sealing the wrong spot doesn't stop water, it just moves it.
Prevention is cheaper than chasing stains. For masonry, a breathable water repellent applied ahead of the wet season (the kind that sheds rain but lets trapped vapor escape) keeps brick from spending the summer saturated; that's the core of chimney waterproofing done right. For crowns showing their age, a proper repair before June closes the single most common leak path. And when a tropical system drags its rain bands across Seminole County (Lake Mary is well inland of any surge, but the wind and sideways rain still arrive), a quick ground-level look at the stack afterward is a habit worth keeping.