Police reduced speed limits in Abu Dhabi as thick fog descended over the emirate early on Thursday.
The bad weather affected an area near Al Ruwais in the west all the way to the capital.
Drivers were told not to exceed 80kph on several roads as visibility dropped below 1 kilometre.
The fog is expected to burn off by about 8am, leaving a hazy and partly cloudy day, which will be warm during the day.
Temperatures will reach 37°C inland and 35°C on the coast.
Winds will be light to moderate.
The sea will be slight to moderate in the Arabian Gulf and slight in Oman Sea.
Friday will be another hot and hazy day, with temperatures of up to 37°C in Abu Dhabi and Dubai.
But the mercury will plunge overnight to reach a maximum of 27°C on Saturday, which could start with mist and fog. Moderate winds, which will be gusty at times, will kick up dust and sand.
Temperatures will remain cooler on Sunday before climbing again.
Last month, the UAE had about 12 days of fog but it was a drier than average month with less rainfall than in years gone by.
In December, President Sheikh Khalifa called for prayers for more.
