An amber warning for snow and ice, with the risk of freezing rain, covers most of Wales and central England until midday on Sunday.
Freezing rain, which makes up what are commonly known as ice storms in North America, is a rarity in the UK because the conditions for it are quite specific, according to the Met Office.
But what is it and how is it different to snow?
Freezing rain is rainfall that has become “supercooled” as it falls from the sky.
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It starts when snow, ice, sleet or hail high up in the atmosphere melts into rain when it falls through the layers of warmer air below.
If the rain then passes through a sub-zero layer of air just above the ground, it can remain liquid and instead become “supercooled”. This is the key to freezing rain.
Supercooled water will freeze on impact – forming a clear layer of ice on cold surfaces such as trees, roads and power lines.
Why is it dangerous?
It’s once it hits the surface and turns to ice that it can pose a real threat.
The ice is very clear, often referred to as black ice, because it is so difficult to see, making it treacherous for pedestrians and drivers.
Freezing rain on a car. Pic: iStock
Sky News meteorologist Kirsty McCabe explains: “The supercooled rain hits the ground and freezes instantly on impact, and that creates a thin layer of ice, also known as glaze, and it’s clear, so you can’t see the ice, which makes it really treacherous.”
If it hits power lines or tree branches, depending on how much rain there has been, the weight of the ice can cause them to break off because they can’t support the weight.
It can also make it difficult to open your car door if there is enough of it.
Get the five-day forecast where you are
Where is it expected to fall?
An amber warning for snow and ice with the risk of freezing rain was put in place from 6pm on Saturday and will remain until midday on Sunday, covering most of Wales and central England, including the Midlands and Liverpool and Manchester in the North West.
But McCabe says it’s Wales where people should be particularly wary of freezing rain.
What precautions should people take?
The best thing people can do is take extra care when travelling. As it is so hard to see, it’s difficult to judge just how icy road surfaces are.
The RAC says freezing rain is arguably the most treacherous of all conditions for motorists.
They urge people not to drive unless necessary, but say those who do need to should check they have plenty of fuel and oil and check their tyre treads.
They also encourage drivers to make sure their lights are working and check they have screenwash.
