The agency said: "On rare occasions, if it [rain] then falls through cold air again just before hitting the ground, the droplets can become ‘supercooled’ and this means that they are still falling in liquid form, even though their temperature has fallen below zero.
It added: "Freezing rain tends to start its life as snow, ice, sleet or hail, but passes through a layer of air that’s above 0 °C on the way down to the ground, melting into a liquid water droplet.
Freezing rain - a rare type of liquid precipitation - freezes the moment it makes impact with a cold surface.
"When this ‘supercooled’ droplet hits the ground (which is below zero too) it spreads out a little on landing, and then instantly freezes, encasing the surface in a layer of clear ice.
Brand new weather maps from WXCharts show patches of freezing rain dotted around the country at 9am on Wednesday, February 19.
