Black Ice: Why a Little Freezing Rain Closes So Many Schools

Picture a road that looks wet but is actually covered in a thin, clear layer of ice. You cannot see it. Cars and buses cannot grip it. That is black ice. It is one of the top reasons schools close.

How freezing rain happens

Snow starts high up in the clouds. On the way down it can fall through a warm layer of air and melt into rain. If the air near the ground is below freezing, the rain drops get super cold. The moment they hit a cold road, car or tree, they freeze into ice.

Weather forecasts call this freezing rain. If the drops are tiny it is called freezing drizzle. Both are bad news for school buses.

Why plows cannot help much

A plow blade pushes snow off the road. Ice is stuck to the road, so the blade just slides over it. Salt helps but it needs time to work. It also works poorly when the road gets very cold. Bridges and overpasses freeze first because cold air hits them from above and below.

Why timing is everything

Freezing rain that falls in the afternoon may melt by the next morning. Freezing rain that falls before sunrise is the worst case. The roads are at their coldest. Buses are heading out. There is no daylight to spot icy patches.

That is why our calculator adds 30 points when it sees freezing rain or freezing drizzle between 3 AM and 7 AM. You will see a blue Black Ice Alert badge when this happens.

Staying safe on icy mornings

• Walk like a penguin: small steps with your weight over your front foot.
• Wear boots with good grip instead of sneakers.
• Stand well back from the road at the bus stop.
• Give drivers extra time and space.
• If school is open, leave early and take it slow.