With temperatures hitting sub-zero, we all know that dreaded feeling of needing to defrost your car in the morning. We have some tips to help!

There are two main reasons that your car might need scraping when it's cold out, and that's because of a hoar frost, or frozen dew.

Simply put, this is just what we usually call frost. It is the physical ice crystals that you can see on a sub-zero object or surface that has come into contact with moist air, as seen in the image above.

When the surface temperature falls below zero, and then below the dew point, the water vapour turns directly into ice as it cools and condenses on that surface.

It's a white-ish sort of colour, and when you can just use the good old-fashioned windscreen scraper to easily get it off, that's definitely a hoar frost.

Frozen dew on the other hand, will likely take you longer to get off your windscreen. It's a thin coating of glaze ice, and is what we are more familiar with, as black ice.

It forms in the same way as regular dew, but in a sub-zero environment. So, the surface temperature falls below the dew point first, allowing dew to form, and then falls below freezing. So the existing dew on the surface freezes over, and is awfully difficult to scrape off.

Sometimes you can have a layer of frost covering a layer of frozen dew beneath, which then just creates double the work!

It's often in this case that people are tempted to bring out their kitchen kettles. Whilst modern wind shields are strong, they can still crack, and the seals can deteriorate faster when subject to rapid temperature changes, so avoid this!

Instead, we suggest a de-icer spray, or a pre-ice spray. Alternatively, you can mix up a concoction of three parts vinegar and one part water, which should keep your screens frost-free by morning. Covers can also do the trick.

But how do you know when to do all of this? Keep an eye on the TemperatureRadar to know when figures may drop away to low single digits (or lower!) under clear skies.