The 50-year-old was shocked after spotting several motorists, and even a pedestrian, using the crossing despite torrential weather conditions.
Video shows a Peugeot 107, shortly followed by a white van, cruising along the crossing as waves of up to 20ft crash over the sea wall.
Heavy wind can be heard howling as it reaches breakneck speed during the dark and cloudy morning on the island.
Although the lamp posts remain on, they can be seen shaking vigorously while being battered by the conditions.
Despite the wind and water howling overhead, the vehicles plough on, undeterred by the endless seawater covering both them and the road.
An anemometer – used for measuring wind speed and direction – can be seen spinning wildly out of control as spray from the sea is sent flying over the causeway.
At one point a series of huge waves break over the wall and are held aloft by the wind, temporarily creating a funnel of water, before crashing down and soaking the road.
The vehicles incredibly manage to get across to the safety of the island as the weather rages on.
Speaking today, Michele, a civil servant from Lemreway, Isle of Lewis, said: “It was pretty awesome to see. It can be bad weather here but I’ve never seen it that bad at the causeway.
“It’s the worst I’ve ever seen it.
“I was working at the time and saw it going on outside my window.
“I filmed the cars driving through it and the weather in general, but I also saw someone actually crossing it at one point.
“I didn’t manage to get him on video as I was too busy watching and making sure he didn’t get blown right off the causeway.”
Western Isles Weather posted one of Michele’s videos showing the high winds on Facebook on Thursday, writing: “Goat Island causeway this morning, shared by Michele Mackay.”
The video has had over 27,000 views and has more than 400 likes.
Dozens of social media users commented on the island’s weather conditions.
Carla Mackay said: “Amazing, the power of the sea.”
Jean Forsyth said: “Love watching the sea like that…when I’m on dry land.”
Jenni Mackay said: “I don’t understand why this is never closed when there are people crossing in cars and walking to get to work.
And Jenet Vlotaros commented: “The weather is fickle…great video.”
Flood warnings were issued by police on the Western Isles on Thursday, with a separate Western Isles weather page detailing winds of up to 60mph.