NOAA’s Climate Prediction Center favors a warm, wet winter for the Mid-Atlantic — a greater than 90% chance of a very strong El Niño through winter 2026-27, with above-normal temperatures and above-normal precipitation both favored along the East Coast. If you heat with a heat pump, that is not the easy winter it sounds like. Mild, damp weather is exactly the range where a heat pump frosts and defrosts most often, which means the defrost system gets exercised more — and any weakness in its sensors, controls or reversing valve is more likely to show itself. A cold winter is more total heating load; a warm, wet one is a different kind of stress, and it lands hardest on heat pumps. Here is what to check before the first real cold snap, and why waiting until December costs you more.

What is NOAA actually forecasting for Maryland this winter?

Two separate documents, worth keeping straight.

On August 13, 2026, the Climate Prediction Center issued an El Niño Advisory: “El Niño is strengthening, with a greater than 90% chance of a very strong event during the Northern Hemisphere fall and winter 2026-27.” The same discussion puts a 69% chance on the October–December value reaching +2.5 °C or higher — stronger than any El Niño on record back to 1950.

That is the ocean. The forecast for our weather is CPC’s seasonal outlook of August 20, 2026, which favors above-normal temperatures across the Mid-Atlantic and Northeast, with probabilities exceeding 50 percent by December–February, plus a tilt toward above-normal precipitation along almost the entire East Coast from November through April.

Warm and wet. Not warm and dry, and not cold and snowy. A seasonal outlook will not tell you what happens the week of January 12th, but it does tell you which failure modes to expect more of — and for heating systems in central Maryland, a warm wet winter and a cold dry one break different parts.

Are heat pumps actually common in central Maryland?

More than most homeowners assume — which is exactly why this forecast matters here.

Anne Arundel County is more electric-heated than its reputation suggests. According to the U.S. Census Bureau’s 2024 American Community Survey, electricity is the primary heating fuel in roughly 52% of occupied homes in the county — ahead of utility gas at about 35% and fuel oil at about 7.5%. The Census question measures the fuel used to heat the home, not the specific equipment, so that figure lumps heat pumps together with electric resistance furnaces and baseboard heat; we cannot read it as “52% have heat pumps.” But University of Maryland Extension identifies air-source heat pumps as the most common type of heat pump in Maryland, and points out that modern cold-climate units perform well through our winters.

That matters for a warm, wet forecast because a heat pump responds to it differently than a gas or oil furnace does. A furnace makes its own heat indoors. A heat pump has an outdoor coil working through the same rain, humidity and near-freezing air NOAA expects more of this winter — which is where the rest of this article spends its time.

Doesn’t a strong El Niño mean a snowy winter in Maryland?

Not according to the people issuing the forecast, no.

Strong El Niño winters do tend to be active along the East Coast — that is the above-normal precipitation signal. But CPC’s own temperature outlook for the Mid-Atlantic leans warm, and precipitation falling into warm air is rain, not snow. BWI’s 1991–2020 normal annual snowfall is 19.3 inches, and nothing in the current outlook forecasts a big snow year here.

What Anne Arundel County sits on is the line. Coastal Annapolis and inland Odenton and Gambrills routinely get different precipitation from the same storm — rain at the water, sleet or freezing rain fifteen miles west. A warm, wet winter does not remove that line; it moves it across the county all season. And the transitional side of it — freezing rain, ice loading, repeated freeze and thaw — is harder on equipment than either extreme.

Why is a warm winter harder on a heat pump than a cold one?

Because of how defrost works.

A heat pump in heating mode runs its outdoor coil colder than the outside air — that is the whole trick, it has to be colder than ambient to absorb heat from it. When that coil drops below freezing and there is moisture in the air, frost forms. Frost insulates the coil, capacity falls, and the system briefly reverses itself to melt the ice off. That is the defrost cycle, and it is normal.

Here is the part that surprises people: the conditions most favorable for frost are not the coldest ones. Frost builds fastest when there is moisture in the air and the coil is still below freezing — in practice, damp weather in the 30s and low 40s. Deep cold air is dry air, holding far less water to deposit on the coil. Exact frosting behavior varies with coil temperature, humidity, airflow and equipment design, but the pattern holds: a system running through 38-degree drizzle defrosts far more often than the same system through a dry 20-degree week.

A warm, wet winter is a winter spent in that band. Three things follow:

The defrost system gets exercised more. The defrost board, the defrost thermostat or sensor, and the reversing valve all cycle on every defrost. More defrost cycles means more chances for a weak reversing valve solenoid or a defrost board with a marginal relay to reveal itself — and it tends to do that during a mild damp stretch, not during a cold snap. Which is why “it worked fine last winter” is not evidence; last winter may not have asked it the same question.

Your bill can go up in a mild winter. Most systems bring on auxiliary heat — electric resistance strips, or the gas side of a dual-fuel setup — during and after a defrost cycle, so the registers do not blow cold. More defrost cycles means more auxiliary heat runtime. If your aux heat stages when it does not need to, you pay for it in a month you assumed you would save.

A failed defrost looks like something else. A system that stops defrosting turns the outdoor coil into a block of ice. What you notice is weak airflow, cold air, or a unit that runs constantly — and most people call that “low on refrigerant.” It usually is not.

If you have a heat pump, the heat pump service page covers what we check and what typically fails. The short version: on a warm wet winter, the defrost side is where to look first.

What does a wet winter do to a gas furnace?

Different system, different failure modes, same root cause: water.

Condensate. A high-efficiency condensing furnace produces water as a byproduct of combustion — that is where the efficiency comes from. It leaves through a drain line, usually with a trap and often a small pump. As furnace runtime climbs, condensate production climbs with it, so a partially restricted trap or a weak pump tends to reveal itself during periods of heavier operation — which is why a clogged drain often trips its safety switch on a cold night, when the furnace has run the most hours. It is one of the most common no-heat calls we take, and one of the most preventable.

Flue draft. Older, naturally vented combustion appliances draft on the temperature difference between the flue gases and the outside air, so chimney draft can be lazier when that difference is smaller — as it is in mild, wet weather. Many high-efficiency furnaces sidestep this entirely with a mechanical induced-draft, direct-vent design. But a marginal naturally vented flue — partially blocked, improperly sloped, or sharing a chimney with a water heater — is likelier to spill combustion products in exactly this weather. That makes venting, chimney condition and a combustion test especially important on older systems. It is a safety issue, not a comfort one.

Short cycling and the secondary heat exchanger. A mild winter means shorter, more frequent burn cycles instead of long steady ones, and more ignition cycles means more wear on the ignitor and flame sensor — two of the cheapest parts on the appliance and two of the most common reasons a furnace will not light. Meanwhile a condensing furnace runs acidic condensate through a secondary heat exchanger, exposing it and the drainage system to corrosion over the life of the equipment. As a furnace ages, that heat-exchanger condition and its drainage become increasingly important inspection points. A furnace in a 1983 house on its second or third decade deserves a real look at that component, not a glance.

Why does a late heating season mean I wait longer for a repair?

Because everyone in the county discovers the problem in the same week.

A warm autumn does not remove heating demand — it delays it. Instead of first cold mornings arriving gradually through October and spreading first-run failures across six weeks, a warm fall compresses them: the first real cold snap arrives, systems across the county start up in earnest for the first time in seven months, and the ones with a bad ignitor or a clogged condensate trap fail within seventy-two hours of each other. That is the week you do not want to be making the call — availability tightens, after-hours rates apply, and parts normally on the truck are suddenly on order.

It is the same logic behind servicing the AC in April rather than June — we wrote that one up here — and the warm forecast makes the argument stronger, not weaker.

What does a heating tune-up actually include?

Here is the checklist, so you can hold whoever you hire to it — the heating-side equivalent of our line-by-line HVAC tune-up breakdown, which covers the cooling checks.

Heating system pre-season inspection — what should be on the invoice

14 items

Applies to gas furnaces, heat pumps, and dual-fuel systems. Items marked F are furnace-only; HP are heat-pump-only.

01Heat exchanger inspectionF — Visual and, where accessible, camera inspection for cracks, corrosion and separation. Any indication of combustion gases entering the supply air requires immediate investigation before the system goes back into normal operation — not a note for next year.

02Combustion checkF — Gas pressure verified against the data plate; combustion analysis at the flue; burner condition and flame pattern.

03Ignitor and flame sensorF — Resistance check on the ignitor; cleaning and microamp reading on the sensor. Two of the cheapest parts on the appliance, and two of the most common ignition-related no-heat causes we see.

04Temperature riseF — Measured supply-minus-return temperature, confirmed within the range printed on the data plate. Outside it means an airflow or gas-input problem.

05Defrost cycle, forced and observedHP — Not “the board looks fine.” The technician initiates a defrost, then confirms the reversing valve shifts, the outdoor fan stops, auxiliary heat engages, and the cycle terminates on temperature rather than on the backup timer.

06Reversing valve and defrost sensorHP — Solenoid function and sensor resistance against spec at measured coil temperature.

07Auxiliary and emergency heat stagingHP — Confirm strip heat stages in correctly and — critically — stages off, rather than running whenever the compressor runs. The most common cause of an unexplained winter electric bill.

08Blower and static pressure — Wheel cleaned, motor amp draw checked, total external static pressure measured and compared against the manufacturer’s rating for your equipment. Many residential systems are rated around 0.5 inches of water column, but that number varies by system. Excessive static pressure reduces airflow, which can contribute to cooling-coil icing, drive up blower workload, and push a furnace to operate against its high-temperature limit.

09Filter — Correct size, direction and MERV for the equipment. One too restrictive for the blower does the same damage as a dirty one.

10Condensate pathF, condensing — Trap cleared, drain line flushed, pump tested, float switch verified. This is the item that keeps a well-run furnace from shutting itself down on its busiest night.

11Safety switches — Rollout, limit, pressure and float switches each tested — not just observed to be present.

12Thermostat and outdoor sensor — Calibration confirmed, staging and balance point reviewed, outdoor sensor verified as reading correctly. A miscalibrated sensor is a direct cause of unnecessary strip heat.

13Electrical — Contactor condition, capacitor microfarads against nameplate, connections tightened, disconnect and breaker sizing confirmed.

14Outdoor unit clearanceHP — Coil cleaned, base pan drain clear, and room for the unit to shed meltwater rather than refreeze in it.

If an invoice says “performed heating tune-up” and nothing else, you cannot tell which of these fourteen happened. Ask for the readings — temperature rise, static pressure, capacitor values, microamps. Numbers are the difference between an inspection and a visit.

How much heating does a central Maryland winter actually demand?

More than the mild-winter framing suggests. BWI’s normal heating degree day total for a full season, July 1 through May 31, is 4,475, and normal daily minimums run 29.6 °F in December, 25.4 °F in January and 26.9 °F in February. A warm winter shaves that total; it does not make it small.

And your system may be working through ductwork older than the equipment attached to it. The median Anne Arundel County home was built in 1983, and roughly 45% of the county’s housing stock predates 1980. In older homes the duct system often predates the current furnace or air handler — which is why the static pressure reading in item 8 tells you more about how your system actually performs than the brand on the equipment does.

What can I check myself this month?

Three things, none of which require a technician. Do them this week.

Your 40-minute pre-heating-season walkthrough

No tools required

1Change the filter and write the date on it. Check the size against the old one, not against memory. If the filter is visibly bowed in its track, replace it and confirm its size and MERV are right for your equipment — persistent bowing points to excessive pressure drop and is worth having the airflow checked.

2Clear three feet around the outdoor unit and rake out everything under it. On a heat pump this matters more in winter than in summer: the unit has to shed meltwater on every defrost cycle, and a base pan sitting in leaf mulch refreezes that water into the coil. Check that nothing drips onto it from the roofline.

3Run the heat for fifteen minutes right now. Set the thermostat above room temperature and let it finish a full cycle. Listen for delayed ignition, a burning-dust smell that does not clear in ten minutes, a grinding or squealing blower, or a system that starts and then shuts off. Check that warm air reaches the far rooms — and on a heat pump, watch the thermostat: if “Emergency Heat” is on, or “Aux Heat” stays on for an extended stretch during mild weather, note it and have the controls checked. A brief appearance during defrost or recovery is normal; a steady one is not.

Anything you turn up is a September phone call, which is a very different call from a December one.

Do I actually need a tune-up every year?

Annual maintenance is a sound baseline — and for some systems it is a warranty condition, not a suggestion.

What the visit needs to include, though, depends on the equipment, its age and its history. A four-year-old furnace with no symptoms may need little more than verification and cleaning; a fifteen-year-old furnace, or a heat pump that gave you defrost trouble, deserves a much closer look. Before you decide to skip a season, check your manufacturer’s maintenance and warranty terms — many require documented annual service, and as a Lennox Premier Dealer we see how a lapse can put coverage at risk.

Where an annual inspection earns its cost:

• Any gas appliance more than ten years old. The heat exchanger and flue checks are safety items, and the two things you cannot assess yourself.

• Any heat pump, every year, and especially this year. A defrost cycle has more moving parts than a gas burner, and this is the winter that exercises all of them.

• Any system that gave you a symptom last winter you never chased down.

• Any system under a warranty requiring documented annual service — many manufacturers’ warranties do, and a denied claim costs more than a decade of tune-ups.

And a tune-up is not a repair. If your heat exchanger is cracked, an inspection finds it but does not fix it. What it buys is finding out in September, when you have options, instead of January, when you have one.

Get a Straight Assessment from Scardina Home Services

Whether you need anything done before winter depends on what you have, how old it is, and what it did last season. We will tell you which of those fourteen items your system actually needs and which it does not — including if the answer is “run it another year.” We service gas furnaces, heat pumps, boilers, oil furnaces and dual-fuel systems as a Lennox Premier Dealer and Mini-Split Specialist, and Jim Scardina — our president, and grandson of the WWII Navy veteran who started this company in 1950 — still runs calls himself.

Call 410.782.0937Request a free estimate online

Scardina Home Services  |  8082 Veterans Highway, Millersville, MD 21108  |  410.782.0937  |  scardinahome.com/services/hvac/heating

Scardina Home Services services and repairs heating systems for homeowners throughout central Maryland — including Annapolis, Arnold, Crofton, Crownsville, Gambrills, Glen Burnie, Lake Shore, Millersville, Odenton, Pasadena, Severn, Severna Park and Columbia, and the surrounding communities in Anne Arundel County.

Sources & References

• NOAA Climate Prediction Center, El Niño/Southern Oscillation (ENSO) Diagnostic Discussion, issued August 13, 2026 — El Niño Advisory; greater than 90% chance of a very strong event during Northern Hemisphere fall and winter 2026-27; 69% chance of a +2.5 °C or greater three-month RONI value for October–December 2026.

• NOAA Climate Prediction Center, Seasonal Outlook Prognostic Discussion, issued August 20, 2026 — above-normal temperatures favored for the Mid-Atlantic and Northeast; tilt toward above-normal precipitation along the East Coast from November–January through February–April.

• National Weather Service, Baltimore/Washington (LWX), BWI Normals, Means and Extremes, 1991–2020 normals — normal daily minimum temperatures and normal annual snowfall.

• National Weather Service, Baltimore/Washington, BWI Monthly Climate Report — normal season heating degree days, July 1 through May 31.

• U.S. Census Bureau, American Community Survey 2019–2023 five-year estimates and QuickFacts: Anne Arundel County, Maryland — median year housing built and age of housing stock.

Forecast figures verified as of September 2026. NOAA updates its ENSO discussion monthly and its seasonal outlook mid-month; check the current issue before relying on any figure above.

Frequently Asked Questions