The leftovers of two Pacific hurricanes are parked over the Front Range this week, and the National Weather Service office in Boulder has a Flood Watch up through Thursday morning. It is the most useful thing a Denver homeowner can hear right now, because the water running into your chimney this week is the same water that will be freezing inside your crown in about five weeks.
Plenty has moved since our last edition. The PUC closed out the Xcel natural gas rate case, and new rates land October 6. NOAA pushed its El Nino call up again. The winter indoor-burning program flips back on November 1. And a new law that pays homeowners to harden their roofs is in effect. Here is what each piece means for the thing on top of your house.
Two hurricanes worth of moisture, a week before the first freeze
The NWS Denver/Boulder office is carrying a Flood Watch and a headline reading FLOODING THREAT TUESDAY NIGHT THROUGH THURSDAY MORNING. The forecast behind it is blunt about the source:
Tropical moisture from the remnants of Odalys and Hurricane Polo will surge over the southwest into the central U.S. this week with several days of heavy to excessive rainfall which may bring limited to considerable flooding. National Weather Service, Denver/Boulder
Multi-day soaking rain is not normal here. We get thunderstorms that dump an inch in twenty minutes and quit. Days of steady rain find the slow leaks instead of the fast ones, and the places it gets in are predictable.
- The crown. That concrete slab on top is the chimney's roof. Hairline cracks that shed a summer downpour will wick a three-day rain straight into the masonry.
- A missing or bent cap. With no cap, rain goes down the flue, mixes with creosote, and eats the liner and damper from the inside. If yours blew off in a spring wind, this is the week you find out. See chimney cap repair and installation.
- Flashing at the roofline. Where the chimney meets shingles is the most common leak on the structure, and it usually shows up as a stain on a bedroom ceiling rather than anything visible outside.
Denver's average first freeze is in early October, which is why this matters more than it would in June. Saturated brick plus a hard freeze is the definition of freeze-thaw damage: water expands, spalls the face off the brick, widens the crack, and takes more water next time. A chimney that goes into winter wet comes out worse. One that goes in dry mostly just gets cold.
The winter outlook: NOAA is calling a possibly historic El Nino
The Climate Prediction Center's September 10 ENSO Diagnostic Discussion kept the El Nino Advisory in place and raised the stakes:
El Niño is strengthening, with a greater than 90% chance of a very strong event during the Northern Hemisphere fall and winter 2026-27. NOAA Climate Prediction Center, ENSO Diagnostic Discussion, September 10, 2026
CPC also puts a 75% chance on October through December producing a historic event, stronger than any El Nino back to 1950, and its September 17 long-lead discussion leans wet for the Four Corners region through spring.
The local read is more measured. In a September 3 post, assistant state climatologist Peter Goble noted there have been three modern super events: 1982-83 buried Colorado, while 1997-98 and 2015-16 came in near average. The Front Range does tend toward more large spring snowstorms in El Nino years, but the link to statewide peak snowpack is weak. CPC adds that the Pacific Decadal Oscillation is strongly negative right now, unlike during those three events, which may blunt the usual fingerprint. More at the Colorado Climate Center.
What this means for your home. Do not plan your chimney around a snow total. Plan it around the two things a storm-heavy winter does regardless of inches: repeated freeze-thaw on masonry, and more days you actually want a fire. Both argue for getting the inspection done before the first real storm, because the week after a big upslope event is when every sweep on the Front Range is booked solid.
Your gas heat gets more expensive on October 6
On September 4 the Colorado PUC issued its final decision in Xcel's natural gas rate case, Proceeding No. 25AL-0538G, approving a settlement that cut the annual revenue increase to $122.7 million from the $190 million Xcel filed for last December. For a residential customer that is an 8.6% increase, about $5.16 a month, instead of the 11.4% and $7.59 originally proposed. New rates take effect October 6. Details are in the PUC's announcement.
What this means for your home. Higher rates make wasted heat more expensive, and a fireplace is one of the biggest heat leaks most Denver houses have. An open masonry firebox with a damper that no longer seals pulls warm air up the flue all winter whether you light a fire or not. Two fixes pay back faster now than they did last winter: get the damper sealing properly, or convert the box to a sealed gas insert, which turns a hole in your envelope into an appliance with real efficiency.
November 1: the metro burn rules switch back on
Air quality is genuinely good this week. The state advisory page showed no advisories in effect and a top AQI of 33 for ozone Monday morning. The winter High Pollution Advisory Program begins November 1, which is when Action Days start being about your fireplace instead of your commute.
During the winter high pollution season (November-March), the graphic indicates whether an air quality Action Day is in effect. During an air quality Action Day, indoor burning is restricted in the seven metro Denver counties. Colorado Department of Public Health and Environment, Indoor burning restrictions
Those seven are Denver, Boulder, Broomfield, Douglas, Jefferson, and the parts of Adams and Arapahoe counties west of Kiowa Creek. Your device is exempt if it is a Phase II EPA-certified stove, an EPA-certified pellet stove, or a Colorado-approved masonry heater, if it sits above 7,000 feet, or if indoor burning is your primary heat and you hold an exemption letter. An open masonry fireplace is not exempt. We keep a plain-language walkthrough at chimney laws and regulations in Colorado.
New state money for roofs, and why it touches your chimney
SB26-155 was signed June 4 and took effect August 12. It creates the Strengthen Colorado Homes Enterprise inside the Division of Insurance, funded by a fee on insurers starting in 2027, with at least 85% of that revenue going to grants that help homeowners retrofit to hail-resistant roofs. Hail, not wildfire, is the target because it is the number one cost driver of homeowners premiums here, running 26% to 54% of an average annual premium. The board is still being seated, so grants are not open yet. See the DOI announcement and the bill at the Colorado General Assembly.
What this means for your home. If a grant eventually helps you re-roof, the chimney is part of that job whether the roofer mentions it or not. Flashing gets cut and re-set, and the crown is right there and easy to seal at the same time. Doing it then costs a fraction of a separate trip.
What we would do before the next edition
- After this rain clears, look for fresh water stains near the chimney chase and white chalky streaks on exterior brick. Both mean water is already inside.
- Look at the top from the ground with binoculars and confirm a cap is there and sitting flat.
- Book the annual sweep and cleaning before the first hard freeze and before the first storm fills every calendar on the Front Range.
- If you have an open masonry fireplace in one of the seven metro counties, decide before November 1 whether you are fine losing burn days or whether a certified insert makes more sense.
- Press the test button on every smoke and CO alarm, not just check the batteries.
If you want eyes on it before the weather turns, get in touch or call us at (720) 207-9232. We would rather look at your crown in October than your ceiling in January.
The Flue Report is published every two weeks by Adam Chimney Sweep, serving Denver and the Colorado Front Range. Edition 6 lands the week of October 12, 2026.
