The first cold overnight of the month is a systems check. Homeowners should flip the thermostat to heat before a hard freeze to confirm the furnace lights, the vents blow, and carbon-monoxide detectors still work with fresh batteries.

Swap the furnace filter if it has been more than three months. A clogged filter makes the blower work harder and raises bills. Vacuuming supply vents and opening closed doors helps heat move through the house.

Energy desks still suggest a moderate setpoint — many comfort guides land near 68°F when people are home and lower when asleep or away — plus sweaters before another thermostat nudge. Smart thermostats help only if schedules are set; otherwise they are expensive clocks.

Windows that rattle need plastic film or weatherstripping before November winds. Renters should ask landlords in writing about furnace service rather than waiting for a no-heat emergency on a Sunday night.

Keep space heaters on hard floors, never on rugs, and plug them directly into wall outlets. They are backup tools, not primary heat, and they drive electric bills fast.

Walk the house at night and feel for drafts at outlets and baseboards. Cheap foam gaskets and door sweeps often pay for themselves in a month of furnace runtime.

Schedule a pro tune-up if the furnace smells dusty or cycles every two minutes. Short-cycling wastes fuel and often means a filter or airflow problem.

What we know: First heat calls of the season coincide with still-elevated energy costs.
What we don't: How early a hard freeze arrives in each region this October.