A wet, stormy July
By late July 2026, the city had been through weeks of repeated thunderstorms. Streets and subway stations flooded, flash flood warnings went up across the five boroughs, and outdoor concerts and games were canceled or delayed. A flood watch covered the city on July 21, and video from a Queens street showed water over the curbs after another downpour. On Long Island, flooding closed lanes of the westbound Long Island Expressway in Roslyn on July 27.
For context, the long-term July average at Central Park is about 4.6 inches. Forecasters expected a quieter pattern to close out the month.
How summer rain reaches the inside of a chimney
Thunderstorm rain rarely falls straight down. Gusts drive it sideways into the face of the brick, and a chimney stands in the open with all four sides exposed. Old, porous brick and soft mortar joints soak it up. A flue without a cap takes water straight down to the damper and the smoke shelf, where it sits in the soot.
Water that gets past a cracked crown can travel down the inside of the masonry and appear far from where it entered: in the firebox, on the chimney breast wallpaper, or in the basement at the cleanout or the thimble where the boiler pipe connects.
Many city chimneys also have flues that no longer serve anything, left over from coal stoves or a boiler that was replaced with a sidewall-vented unit. Those abandoned flues are often open at the top and closed off at the bottom with a metal plate or a stuffed rag. Rain collects at the base, soaks the brick and shows up as a damp patch on the wall of an upstairs room or in the basement.
Why the fireplace smells in July
A common summer complaint is a sour, smoky or musty smell coming from a fireplace that has not been used since spring. Creosote and soot left in the flue absorb moisture when the air is humid and after rain. In a tightly sealed house, air conditioning and kitchen or bath fans can pull air down the chimney, bringing that odor into the room.
Sweeping the flue removes most of the source. A cap keeps rain off the smoke shelf, and a damper that actually seals, or a top-sealing damper at the crown, stops the air from moving down the flue when the fireplace is not in use.
What to check before fall
Summer is a practical time to fix what the storms revealed: a stain on the chimney breast, a rusty damper, water in the firebox, or brick that stays dark long after the rain stops. Repairs to crowns and mortar set up properly in warm weather, well before the first freeze puts water in those cracks to work.
Downpours like these also test the flashing on flat rowhouse roofs, where water can pond around the chimney after a heavy storm. A puddle that sits against the brick for hours is a slow leak waiting for a weak seam.
Want a professional look? See our chimney odor removal service, or call (844) 468-2410 for a free written estimate.
