Lakeland's name is literal (38 named lakes inside the city), and all that water keeps the air perpetually loaded. Masonry in lake country never really dries out between June and October: brick absorbs, mortar stays damp, and any crack in a crown or cap becomes a standing invitation. Moisture is the slow, patient force behind most of the chimney damage associated in Polk County.
The fast, violent force is lightning. The Tampa-to-Orlando corridor is among the most lightning-prone areas in the entire country, and Lakeland sits square in the middle of it. A chimney is often the tallest point on the house, and a strike, even a near one, can crack a crown, blow out mortar joints, or shift a cap. After any close hit, the chimney deserves a look from top to bottom, because lightning damage loves to hide until the next storm turns it into a leak.
Summer storms also do their ordinary daily work: wind-driven rain against the stack, water probing the flashing, debris slapping at the cap. By September, a chimney that entered June with a hairline crack has had a hundred storms' worth of water pushed through it. That's why the smart season for an inspection here is spring or early summer. Find the cracks before the rain finds them.
Humidity leaves fingerprints too. In the lake neighborhoods, the shaded north face of a chimney often grows a gray-green film of mildew and algae the sunny side never shows, and persistent damp softens old mortar joints ahead of schedule. It's mostly cosmetic, but it's also a marker of masonry that stays wet, and masonry that stays wet is masonry aging on fast-forward. A breathable repellent slows the whole process down considerably.