It is one of the largest gatherings of people of its kind, with an estimated two million coming together for what is the journey of a lifetime for many.
But amid the baking sun and thronging crowds, how do pilgrims stay cool and hydrated?
From policemen spraying cool water from backpack-mounted hoses to air-conditioned marble floors, Hajj officials are attempting to make the summer heat of Mecca as manageable as possible. And last week it was announced that huge folding umbrellas will be installed in the courtyards of the Grand Mosque.
“Just when I thought I could not take it anymore, the police officers come spraying water, cold and refreshing," said Jordanian Zayed Al Dakheel, 37, of his Hajj last year.
"When you have been walking for 500 metres and you are sprayed with this water, it boosts your energy to continue, it is like taking a dose of energy.
“As soon as people spot the water police, they would race towards them, you’ll see dozens gathering around one policeman; some would also ask him to shower them from head to toe.”
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This week, about two million pilgrims will converge on Mecca, presenting the Saudi authorities with a unique logistical challenge.
In between the heavy crowding and exhaustion pilgrims have to go through in order to complete their Hajj pillars, a little water is “like a gift from God”, said the 37-year-old from Jordan.
Inside Al Haram – where the sacred Kaaba lies and worshippers perform Tawaf and Saai - the marble floor remains cool, due to powerful air-conditioning from underneath.
There are fans all across and the covered areas of the mosque are air-conditioned.
It is also common practice for pilgrims, or benefactors in general, to buy boxes of water, juice or fruits from supermarket in Mecca so they can be distributed for free to pilgrims. Trucks drive around Mount Arafat to distribute refreshments.
“We were walking towards the Haram and it was very hot and the distance was far, then a man offered to drop us in his air-conditioned van," said Mr Al Dakheel.
“There were also motorists volunteering rides to pilgrims. When we asked how much, he said it was voluntary and just asked us to pray for him.”
Such vans and micro-buses were quite common, he added.
The UAE's Hajj mission team has been investing in new facilities to provide pilgrims respite.
“For the first time in Arafat history, a 25-tonne air-conditioning unit is being added to a tent,” said Abdulrahman Al Tunaiji, from the UAE Hajj mission.
“Each tent has four units of AC, adding up to 100 tons. The temperature inside the tent can drop down to 18 degrees.”
In addition, fans that spray water have been added across the pathways between tents at the UAE camp sites. The mission has also prepared power generators to supply all of their camps in case they run out of power. This year a total of 6,228 Emiratis have been granted approval to perform Hajj – in addition to 400 pilgrims who work for the mission.
“Umbrellas that are equipped with fans can also be found at the market in Mecca," Al Tunaiji added.
As for the Haram itself, he said it has been equipped with a cooling system that works on many levels.
Physical changes have also been made to the Haram to congestion.
Moreover, the new levels that have been built at the Jamarat – where pilgrims perform the stoning – to eased congestion to a great extent.
“Now pilgrims can go up to the second or third level to avoid overcrowding, only older pilgrims and those who cannot climb the stairs remain on the ground level,” explained Mr Al Dakheel.
“The marble is cooled, there are fans all around the Haram, inside and outside,” said Mira Mohammed, an Emirati pilgrim, who arrived in Mecca on Saturday to perform Hajj for the first time.
She added that she was provided with a fanned umbrella that sprays water from her Hajj agency.
“It is called the 'Mecca umbrella', but we have not used it yet. I think it will be helpful later in Mina and Arafa,” she added.