Explainer: How effective is salt on roads in extreme cold?

An arctic blast will move into the Mid State early next week
WSMV4's First Alert Meteorologist Cruz Medina explains how effective salt can be in extreme cold.
By Cruz MedinaPublished: Jan. 10, 2024 at 4:34 PM CST|Updated: Jan. 10, 2024 at 4:54 PM CSTEmail This LinkShare on FacebookShare on X (formerly Twitter)Share on PinterestShare on LinkedIn

NASHVILLE, Tenn. (WSMV) - The colder it gets, the less effective road salt becomes.

We’ve been telling you about the extreme cold that’ll arrive early next week. With temperatures as cold as they’re going to be, using salt to treat roads and property ahead of time might not be as effective as you think.

Road salt/brine mixtures become less effective in extreme cold temperatures.
Road salt/brine mixtures become less effective in extreme cold temperatures.(Federal Highway Administration)

Water freezes at 32°, but the colder it gets, the more difficult it is to get salt to work effectively. Salt performance is even worse with temperatures below 25°, and virtually ineffective below 15°.

Low temperatures early next week could actually be in the single digits which could really make salt/brine ineffective.

Additional chemicals would have to be added to the salt that are capable of lowering the freezing point of water more than road salt does.

A study done by Marquette University on road salt showed that pre-wetting the salt, like the Department of Transportation does, can improve salt’s performance at low temperatures.

For personal use, most people could not afford the costs of liquid application systems. They also require a lot of maintenance.

Calcium chloride, magnesium chloride, and potassium chloride are all effective chemicals at lowering the freezing point of water, but are more expensive, therefore they aren’t used as often.

The above mentioned chlorides are capable of keeping roads in good condition even if temperature do drop below that 15° threshold and that’s because they can lower the melting point of water better that sodium chloride (salt) can.

Calcium chloride, magnesium chloride, and potassium chloride are also more environmentally friendly compared to the most commonly used deicer, sodium chloride.

Rock salt, like sodium chloride, aren’t purified and contain contaminants like lead, iron, aluminum, and phosphorous that can end up in our groundwater.

Road salts can be effective in extreme cold if there is direct sunlight shinning on it. At nighttime is when road salts are much less effective in extreme cold.

Most Read

A truck hit and killed a motorcyclist late Thursday night and drove away.
Truck hits, kills motorcyclist on I-40 before driving away
Asher Sullivan
‘We love you, Asher’: Family provides update on boy swept into storm drain
Scottie Scheffler warms up before the second round of the PGA Championship golf tournament at...
Scottie Scheffler, charged with assault after officer dragged near fatal crash, tees off at PGA Championship
Headstones ran over after vehicle vandalizes Tennessee cemetery
Headstones ran over after vehicle vandalizes Tennessee cemetery
FILE - Elle King performs during CMA Fest 2022 on Sunday, June 12, 2022, at Nissan Stadium in...
Elle King ‘mortified’ about her drunken performance at Dolly Parton tribute concert

Latest News

Wilson County Sheriff's Office
Man found guilty of killing Mt. Juliet teen on his 19th birthday
File photo of a Metro Nashville Police Department patrol vehicle
Person hospitalized after shooting in Antioch
A Columbia State professor is missing after being washed away by a wave while walking along an...
Columbia State professor missing in Brazil, 3 Tennessee community college students injured
Man wanted for criminal homicide
Nashville Mayor Freddie O'Connell said license plate readers could return to the city.
Mayor O’Connell says license plate readers could return to Nashville