Refreeze: Why a Lot That Was Clear at 6 p.m. Is Ice at 6 a.m.
October 27, 2026 · JRW Services LLC
Why a plowed commercial lot turns to ice overnight: meltwater, pile runoff, shade and pavement temperature, and how a snow contract should handle refreeze.
The storm ended in the morning. The lot was plowed, salted and looked great by afternoon. The sun came out, the gutters ran, and by 6 p.m. the pavement was wet and black. At 6 a.m. the next day, the first employee in slips on a sheet of ice in the same drive lane.
Nobody skipped anything. This is refreeze, and on a lot of commercial properties it causes more falls than the storm itself, because the storm is obvious and the ice the next morning is not.
Why does ice form overnight on a plowed parking lot?
Ice needs two things: water on the pavement and a pavement surface below freezing. A cleared lot on a sunny afternoon after a storm has plenty of water, and it gets it from more places than you might expect.
The film a plow leaves behind. A plow blade does not scrape pavement perfectly clean. It leaves a thin layer in low spots, in cracks and wherever the blade rides over a bump. Sun melts it into a wet film that looks harmless.
Snow piles. Every pile on the property is a reservoir. It melts in the daytime and the water runs downhill, across whatever sits below it. A pile at the high end of a lot quietly feeds a sheet of water across the drive lanes every afternoon for as long as it exists.
Roofs and downspouts. Snow on the roof melts from the heat of the building and the sun. Downspouts that discharge onto a sidewalk or into a parking lot put water right where people walk. Drip lines along canopies and overhangs do the same thing at entrances.
Diluted salt. Salt works by turning ice into brine, and brine has a lower freezing point than water. But as more meltwater runs into a treated area, it dilutes that brine. By evening, a surface that was salted in the morning can be covered in water that is mostly water, and it freezes like water.
Pavement temperature is not the forecast
The overnight low in the forecast is an air temperature, measured above the ground in shade. What decides whether the wet film freezes is the temperature of the pavement itself, and the two can be well apart. Pavement loses heat quickly on a clear, calm night. It can drop below freezing while the air is still reading a degree or two above.
That is why refreeze can hit on a night that did not look cold enough on a phone. It is also why the choice of material for a refreeze treatment depends on how cold the surface will get. Our post on the temperature where salt stops working covers that side of it.
Shade and wind make certain spots predictable
Refreeze is not random. The same spots ice up night after night:
- North facing entrances and walkways that never get direct sun.
- The shadow side of the building, and areas under canopies.
- Loading docks and ramps, especially sloped ones.
- Low spots where water collects and has nowhere to drain.
- Anywhere downhill of a snow pile or downspout.
- Drive lanes next to a tall building or a tree line that blocks late-day sun.
Once you know where they are, they belong on the site plan as treatment priorities. We find most of them on the pre-season walk, and the rest show up the first week of winter.
How a snow contract should handle refreeze
A lot of snow contracts are written around snowfall: a trigger depth starts a visit and the visit ends when the lot is clear. Refreeze does not fit that model, because it happens on a night with no snowfall at all. If the contract does not say how refreeze is handled, it is often handled by a phone call from the property after someone has already slipped.
Here is what to settle in writing:
Who watches for it. The contractor should be monitoring post-storm temperatures and conditions, not waiting for the property to call.
What triggers a refreeze visit. Wet pavement, a falling temperature and daytime melt are the classic setup. The plan should say that a post-storm check happens under those conditions, and which areas get treated first.
How it is paid for. On a seasonal contract, salting may be inside the flat rate or billed per application. Either works. What matters is that the proposal says which one, and that refreeze treatments are clearly part of it, so nobody hesitates to send a truck at 4 a.m. over a billing question. Our salting and de-icing page explains how we set this up.
Where the piles go. Piles belong on the low side of the lot near a drain that stays open, so meltwater goes into the storm system instead of across traffic. That decision is made before the season, not in January. See where snow piles go on a commercial lot.
What the property fixes. Some refreeze is a building problem, not a snow problem. A downspout that dumps onto a walkway, a clogged catch basin, or a low spot at the front door will ice no matter how good the contractor is. The walkthrough should flag those so the property can fix them, and until they are fixed, they get extra attention in the plan.
Documentation matters most on the quiet nights
When a slip happens the morning after a storm, the questions are about the night before. Was anyone watching? Was the lot treated after the melt? When? A service report that logs post-storm checks and treatments, with times and areas, answers those questions. A contract that only covered the storm cannot. Our sample service report shows how we record every visit, including refreeze treatments.
Plan for the night after the storm
We build refreeze checks, problem areas and pile locations into the written site plan for each property. If your lot has spots that ice up every morning, call (973) 459-0074 or request a free site assessment and we will walk it with you before the season.
Common questions
Why does my parking lot ice over after it has been plowed and salted? Daytime melt from plow residue, snow piles and roofs puts water on the pavement, and meltwater dilutes the salt already there. When the pavement drops below freezing overnight, that water refreezes.
Can pavement freeze when the air temperature is above freezing? Yes. The forecast low is an air temperature measured in shade, and pavement can lose heat quickly on a clear, calm night and drop below freezing while the air is still a degree or two above.
Does a snow contract cover refreeze? Only if it says so. The contract should state who monitors post-storm conditions, what triggers a refreeze visit, and whether those treatments are inside the seasonal rate or billed per application.
Where do the icy spots usually form? North facing entrances, shaded areas, loading docks and ramps, low spots that do not drain, and anywhere downhill of a snow pile or downspout. Those spots belong on the site plan as treatment priorities.
Looking for a contractor that is prepared for the worst?
That is the whole way we run. Fill out the form or call (973) 459-0074, and we will walk your property and build the plan before the first storm.