The sighting of the Suhail star over central Arabia traditionally marks the shift towards cooler weather and it was seen last night at about 5am.
The Astronomy Centre announced its appearance on Twitter, with a picture.
But residents should not expect an immediate return to good weather, as the traditional 365-day Emirati Al Drour calendar predicts a delay of 70 to 80 days after the astronomical event.
The Suhail star is the second-brightest star in the sky after Sirius and once guided pearl divers and Hajj pilgrims as they navigated at night.
Known as Canopus in the West, it is still used today, in space navigation.
Despite the star’s appearance, the heat continued in the UAE on Tuesday, with temperatures forecast to peak at 46ºC inland on Wednesday, before cooling to a humid 27ºC.
On Monday, the National Centre of Meteorology urged people to prepare for sandstorms, dust clouds and reduced visibility on the roads this week.
Light to moderate winds are forecast for Wednesday and could increase on Thursday, with gusts of up to 40 km/h blowing dust.
Fog and mist could form on Friday morning over some coastal and internal areas, particularly in the west.