Colorado's October Temperature Whiplash Is Creating a Thermostat Dilemma for Castle Rock Homeowners

Oct 18, 2026

After an 80-degree day, a first freeze and a rebound to the 70s in one week, Alpha Air Heating & Cooling explains how to set a thermostat for cold mornings and warm afternoons without making the system fight itself.

Castle Rock, Colorado Oct 17, 2026 (Issuewire.com) - In the span of one week, the Front Range went from record October warmth to its first freeze and back toward the 70s. Alpha Air Heating & Cooling, a technician-owned HVAC company in Castle Rock, says that swing is leaving homeowners with a question that comes up every fall but rarely gets a straight answer: what should the thermostat actually be set to right now?

The National Weather Service recorded a high of 80 degrees in Denver on October 12, part of the longest stretch of 80-degree days on record for the month. The next day, a cold front cut the high to about 65. Rain followed on the plains, the mountains picked up snow, and forecasters expected the season's first freeze across much of the plains late Thursday night into Friday. By the weekend, highs were forecast back in the 70s. Castle Rock sits higher than Denver and tends to run colder overnight, which only widens the gap between a cold morning and a warm afternoon.

"This is the time of year people call and tell us their system is acting strange, and most of the time nothing is broken," said Kyle Myers, owner and lead technician at Alpha Air Heating & Cooling. "The house needs heat at 6 a.m., the sun is pouring through the windows by 2 p.m., and the thermostat is stuck in the middle trying to handle both. How you set it up for these few weeks matters more than most people think."

The most common problem is a thermostat set to automatic changeover with the heating and cooling setpoints too close together. The furnace warms the house in the morning, the afternoon sun pushes it a degree or two past the cooling setpoint, and the air conditioner turns on to undo the heat the furnace just made. Myers recommends keeping a gap of several degrees between the two setpoints if auto mode is used. For many homes, the simpler answer through October is to leave the system in heat mode, set a modest morning temperature, and let the afternoon sun carry the house rather than switching to cooling for a few warm hours.

The second issue is short cycling. On mild days, the heating demand is small, and a furnace built for January can reach the set temperature in a few minutes, shut off, and start again shortly after. Startup is the hardest part of a heating cycle on the equipment, so dozens of short runs a day add wear. A schedule that warms the house before the family wakes up and then lets the temperature drift down a few degrees during the day cuts the number of starts. Rapid cycling that continues even on cold days is a different matter and can point to a clogged filter, a thermostat in a poor location, or a system that is too large for the home.

Windows matter too. Letting morning sun into south-facing rooms adds free heat on a cold start, while closing blinds on west-facing windows in the late afternoon keeps the house from overheating and triggering the cooling side.

Alpha Air also notes what homeowners should expect when the furnace runs for the first time this season. A faint burning smell for the first few minutes is usually dust burning off the heat exchanger and is normal. A smell that lingers, gets stronger, or smells like gas is not. For a gas smell, homeowners should leave the house and call the gas utility from outside before calling an HVAC company. Changing the air filter before regular heating begins is the easiest step to keep the system running properly.

For homes with rooms that never seem to match the rest of the house, the company points to ductless mini-split systems, which heat or cool individual rooms and adjust their output instead of switching fully on and off. On days like these, that allows a sunny room to be cooled while a shaded bedroom stays warm.

"You don't need to buy anything to get through October," Myers said. "Most of what people deal with this time of year comes down to settings. If you fix the settings and the system still isn't keeping up, that's when it's worth having someone take a look."

Alpha Air Heating & Cooling was established in 2022 by Myers after nearly a decade in the trade. He holds NATE certifications in gas heating service and installation and air conditioning service and installation, universal EPA certification, and an F-29 master mechanical license. The company provides furnace repair and installation, air conditioning repair and installation, and ductless mini-split services across Castle Rock, Castle Pines, Highlands Ranch, Parker, and Lone Tree.

Homeowners with questions about thermostat settings, or a system that cycles more than it should, can contact Alpha Air Heating & Cooling at (720) 284-9566 or visit alphaairco.com.

About Alpha Air Heating & Cooling
Alpha Air Heating & Cooling is a technician-owned residential heating and cooling company serving Castle Rock and surrounding Douglas County communities. Founded in 2022, the company provides furnace and air conditioning repair and installation along with ductless mini-split services.

Contact:
Alpha Air Heating & Cooling
Castle Rock, CO
(720) 284-9566
https://alphaairco.com/