Speed limits were reduced on major roads in Abu Dhabi and Dubai as thick fog descended across almost the entire country during the early hours.
The blanket stretched all the way from the coast to deep inland, almost reaching the UAE’s borders in the south.
Forecasters issued a red alert as visibility dropped to less than 1,000m, and police warned drivers not to exceed 80kph.
First introduced in 2019, the variable speed limit system is activated during bouts of bad weather, such as heavy rain, fog or during sandstorms. Anyone driving faster than 80kph when the change is in place will be fined.
The decision to activate it is made using weather reports, sensors installed on smart gates that estimate the visibility range and reports from police patrols.
The fog season begins in mid-December and runs until the end of March, aided by clear skies and calm conditions.
Tuesday's fog is expected to lift by 10am, leaving a partly cloudy day.
The bad weather means there will be a chilly start, with many parts struggling to reach 10°C.
Temperatures will be cooler even after the sun rises, especially in the west, but could reach up to 26°C on the coast and 27°C inland.
Winds will be light to moderate.
Conditions will be moderate in the Arabian Gulf and slight to moderate in the Oman Sea.
Humidity will rise again overnight, raising the risk of further mist and fog on Wednesday, and again on Thursday.
The end of the week is expected to be dusty, partly cloudy and colder than previous days.
The decrease will be most noticeable on Friday. Saturday will still be dusty and cloudy, but temperatures will begin to climb again.