Why is the rain dirty? How the Saharan dust cloud is affecting the UK today and what causes it
People across the UK have woken up to find their cars covered in a fine layer of dust, due to the arrival of “dust rain” from a Saharan dust cloud.
“Actually made the effort to wash our cars last night and now we’ve woken up to a shower of dust absolutely everywhere, why do I bother?” lamented Georgia on X, formerly known as Twitter.
Laura, another user of the social media platform, added: “Have we had a Saharan dust storm or something? My car is caked this morning.”
The Met Office said on Monday that Saharan dust is “likely to extend across parts of the UK this week”.
The dust cloud comes amid a September heatwave that has pushed temperatures above 30ºC in much of the country. There is a chance the highest temperature of the year so far – 32.2°C recorded on 10 June – could be surpassed on Thursday.
What is dust rain?
Saharan dust is a mixture of sand and dust from the Sahara, the vast desert area that covers most of North Africa.
When big dust storms in the Sahara coincide with southerly wind patterns they can travel to the UK. This is relatively common, happening multiple times per year.
Showers then bring this dust down to Earth’s surface, becoming very noticeable when it settles on cars and windows. These showers are sometimes referred to as “dust rain” or “blood rain”, due to the colour of the residue they leave.
The Met Office explains: “As in other parts of the world, the wind can blow strongly over deserts – whipping up dust and sand high into the sky. If the winds in the upper part of the atmosphere are blowing north, the dust can be carried as far as the UK.
“Once it is lifted from the ground by strong winds, clouds of dust can reach very high altitudes and be transported worldwide, covering thousands of miles.
“In order for the dust to get from up in the sky down to the ground, you need something to wash it out of the sky – rain. As raindrops fall, they collect particles of dust on the way down. Then when the raindrops land on something and eventually evaporate, they leave behind a layer of dust.”
While you’re car being caked in dust can be somewhat irritating, a happier consequence of Saharan dust clouds can be stunning sunsets, with light reflecting off the reddish dust to create vibrant hues.
What is the latest weather forecast?
The hot weather is expected to continue through the week and into the weekend, particularly in southern parts, though there is a chance of some thundery showers.
Met Office chief meteorologist Neil Armstrong said: “High pressure is situated to the south-east of the UK, which is bringing more settled conditions and temperatures well above average for the time of year. While the highest temperatures are expected in the South, heatwave conditions are likely across much of England and Wales especially, with parts of Scotland and Northern Ireland also likely to see some unseasonably high temperatures.
“An active tropical cyclone season in the North Atlantic has helped to amplify the pattern across the North Atlantic, pushing the jet stream well to the north of the UK, allowing some very warm air to be drawn north. It’s a marked contrast to the much of meteorological summer, when the UK was on the northern side of the jet stream with cooler air and more unsettled weather.”
The higher temperatures are due to peak on Thursday, but temperatures and humidity will remain high for many in the South into the weekend, the Met Office said, and there’s an increasing chance of some intense thundery downpours, most likely in the West.
Met Office deputy chief meteorologist Steven Keates said: “A cold front will begin to influence things from the north-west towards the weekend, though it’ll remain very warm or hot in the south.
“There’s a chance the thunderstorm risk to western areas from Friday onwards may require a warning response, with some potentially impactful downpours, though exact details on the likely positioning of these downpours are still being determined.”
The exception to the largely very warm conditions is in the far north and west of Scotland, which will see some showery periods.
