Video report by ITV News Correspondent Graham Stothard
Residents in Edinburgh were awoken by a "terrifying" bang and a crash on Friday morning caused by a massive "thundersnow" storm hitting the city.
Social media lit up in the early hours with bleary eyed Scots reporting a noise like "a bomb," "an explosion," and even "a sonic boom".
Police Scotland even issued a statement urging the public "not to be alarmed" and stressing "we are currently experiencing thunder and lightning."
Thundersnow doesn't happen very often but early Friday morning, parts of Scotland woke to not only the white stuff, but loud thunder and bright lightning in the air too.
It took many by surprise, the thunder so loud, it woke up residents in Perth and Edinburgh.
What sounded like an explosion, this rare weather phenomenon is actually caused when the air close to the ground is warm enough to cause a thunderstorm, while the cold air above produces snow.
The snow enhances the lightning, it appears brighter than normal - that's because it reflects and bounces off the snowflakes.
In a typical thunderstorm, the thunder can be heard many miles away, but in a thundersnow event, the sound is only heard if you are within two to three miles of the lightning.
So this explains the explosive sound and the rude awakening for some. The weekend is set to remain cold, a little less snow in the forecast so we probably won’t see this rare phenomenon in the UK anytime soon.
The force received a number of calls around 5am Friday as the storm moved over the city.
Weather buffs soon joined in the conversation, explaining the city was experiencing thundersnow.
The weather phenomenon has all the same markings of a thunderstorm, but rather than rain, snow falls instead.
Robert MacRae managed to capture the sound on his snoring app.
In Leith, Mrs G wrote: "Wide awake now full of adrenaline after getting woken up by thundersnow and it is by far the craziest loudest thing ever. Set car alarms off!"
"Never knew that was a thing?" wrote Senor Fandango on Twitter.
Another tweeted: "Anyway I can now confirm that in the event I get woken up by what I think is the world ending, my first reaction would be to check Twitter to make sure."
Others said they had rushed onto social media to check the "apocalypse" had not arrived.
Parents united on Twitter too, with many despairing that the two huge booms had awoken sleeping babies.
Not to be left out, Londoners joined in the early morning Twitter exchange, expressing envy the South had seen no snow overnight.
But Londoners could still see some snow on Friday, with the Met Office warning of snow and heavy rain for the east of England plus London and the South East.
The Met Office said the cold spell is expected to last through to Friday but that the weekend would see brighter weather and even some sunshine.