Almost nobody in the Puget Sound, Willamette or lower Columbia valleys should install a heated driveway. Seattle-Tacoma averages 6.8 in of snow a year and records measurable snow on 4.6 days (NOAA 1991–2020 normals, station USW00024233); Portland averages 4.3 in on 4.4 days. A $3,200–$10,000 installation would sit idle for eleven months and then handle two or three inches. This page exists to say that with numbers attached, and then to describe the much smaller thing that is worth buying.

The verdict here is “keeps up”, and it is not a reason to buy

Our melt-capability computation returns keeps up for this zone, comfortably. The design day — the deepest daily snowfall threshold Sea-Tac crosses at least once a year — is 1 in, the smallest on the site, recorded on 2.2 days. At the 2 in/hr melt rate every portable mat claims for itself that clears in 30 minutes. Annual snowfall at the same claimed rate gives 3.4 hours of running across a whole year.

Read that carefully, because it is the clearest example on this site of a verdict answering a narrower question than the one a buyer is asking. Keeps up means the equipment’s own marketing claim is adequate for the snow that falls. It was never a statement about whether the purchase makes sense. Here the capability was never the binding constraint — the frequency is — and a verdict that only measures capability will say yes in exactly the zone where the answer is no.

What an install costs per snow day

Embedded electric cable is published at $8–$25 per square foot installed, materials and labour, by WarmlyYours on a page dated 2026-07-02. For a 400 sq ft two-car driveway that is $3,200–$10,000.

Sea-Tac’s 2.2 snow days a year come to about 22 across a decade. Dividing the published install range by the published event count over that horizon gives $145 to $455 per snow day. The same arithmetic in the Northern Plains, at 14.6 snow days a year, gives $22–$68. Nothing about the equipment differs; the number of times it has anything to do differs by nearly seven.

Running cost is not the argument either way. That 400 sq ft system draws 16.4–20.04 kW (41–50.09 W/sq ft across our embedded records, multiplied by area — derived, not a manufacturer figure), and 3.4 hours a year of it is 56–68 kWh, or roughly $8–$10 a season at the zone’s 14.24 cents/kWh. A design-day storm costs $1.17–$1.43. Those are the smallest operating figures on the site and they are beside the point: the capital cost is what you would be buying, and it does not amortise across two snow days a year.

For contrast, WarmlyYours’ own runtime cross-check for that system is 50–120 hours a season, which would be $117–$342 here. Their figure was built for markets with real winters. This zone’s published normals produce 3.4 hours. We show both, and the size of the gap is itself the finding.

Four and a half days of snow a year

The event counts are worth reading directly rather than through an annual total. Sea-Tac records 4.6 days a year with at least 0.1 in of snow, 2.2 with an inch, 0.7 with three inches, and 0.3 with five — that last one being roughly one winter in three. Portland is thinner still: 4.4, 1.6, 0.2 and 0.1.

The storms people here remember are the 0.3-day and 0.1-day events, and our design day deliberately excludes anything crossed less than once a year. So the verdict above describes an ordinary Puget Sound winter, not the one that shuts the region down. A 5 in fall at the claimed 2 in/hr would need 2.5 hours of continuous running — the same as a Buffalo design day. It is a real event and it is rare, and buying a permanent installation for something that happens every third year is the definition of the case this page is arguing against.

The hazard we cannot put a number on

The local complaint here is not depth, it is wet snow near freezing and the ice that follows it. Our data has nothing to say about that: heavyWetSnowShare is null on all 14 zones because no source publishes it on a basis comparable to the NOAA normals everything else here rests on, and typicalStormIntensityInPerHr is null for the same reason.

That is a genuine gap and it cuts toward heating rather than against it — a surface held above freezing is doing something on a wet-snow day that an annual snowfall total does not capture. We are still not going to price it, because the honest position is that we have no figure, and a plausible one would be an invention.

What is actually worth buying here

A single heated doormat or stair tread, for the two or three mornings a year that matter. These are the published figures from our records:

Amperage is published for every one of those. Wattage is not, on any of them, and we will not multiply volts by amps and call the result watts: 1.9 A at 120 V is 228 VA of apparent power, a different quantity. Our storm cost tool shows that band and labels it as apparent power rather than converting it. Our layout planner deliberately excludes doormats from driveway coverage — they publish amps, so nothing stopped them being offered until we excluded them by product type, and a driveway covered in entrance mats was never a real answer.

At $179.99 for a mat that gets used three mornings a year, the case is convenience at the one place it matters — the step you carry groceries over — not snow clearing at any scale.

Who should not buy, and who might

Should not: anyone here considering an embedded system for a driveway, on the arithmetic above. Anyone buying against the once-in-three-winters storm, since a permanent install is a poor instrument for a rare event and a plow call is cheaper than $3,200. And anyone expecting any of this to make a surface safe underfoot — reducing accumulation is what these products are specified to do, and not one of them publishes a claim about traction.

Might: someone with steps they must use in the dark on the few icy mornings a year, particularly where a fall would be serious. That is a small, specific, honest case, and it is a $100–$400 purchase rather than a five-figure one. Our break-even calculator exists for the bigger decision, and in this zone we would expect it to tell you not to make it.