Dozens of flights were cancelled, diverted or delayed at the three main airports in the emirates of Abu Dhabi, Dubai and Sharjah.
At the Dubai airport, one of the busiest in the world, at least 17 flights were cancelled, as visibility dropped to just 100 metres in some areas of the emirate.
At least another 100 incoming flights were either diverted to nearby airports or delayed, according to the flight schedule at the airport.
Dubai carrier Emirates Airlines, which has a fleet of over 250 large planes, said it has cancelled 10 flight departures.
More From This Section
The fog has engulfed most of the country since Friday, but it intensified overnight as relative humidity soared to 95 percent amid cold winter weather.
Police warned motorists to be extremely cautious when driving in the fog, which the UAE weather centre has said is likely to continue until the end of the day.
The United Arab Emirates has a native population of just one million against nine million foreigners, most of them from the Indian subcontinent.