They are arriving in droves, on foot, by donkey, or in matatus – the crowded minibuses that crisscross Somalia's border with Kenya.
Some 18,000 refugees have left their homes in Somalia this year for Dadaab's sprawling city of sticks.
Here they are handed cooking utensils and plastic sheets to fashion a simple shelter from acacia branches.
Some fled Somalia's capital Mogadishu in late May, at the height of clashes between Islamist militias and the city's hated warlords. Others fled later, as the triumphant Islamists began to shut down cinemas showing Western movies, threatened rapists with stoning, and imposed hard-line Islamic law on areas under their control.
Now, with the Islamists strengthening their grip on the country, and the Transitional Federal Government teetering close to collapse, the threat of full-scale war keeps a steady stream of people arriving at this sprawling refugee camp.
"There is not much here, but I came because we heard that the refugee camps were peaceful," says Noorto Ibrahim Hassan, her lips quivering beneath a vivid green hijab that covers her head.
In the shade of her makeshift home, built from plastic sheets stretched over sticks bent into a dome, she explains how she and her family endured the anarchy of Mogadishu for 15 years after the collapse of the country's last functioning government.
They stayed in after dark and avoided the city's warlord-run roadblocks as much as possible, staying in their own part of town.
But the final straw came in early June, when the Islamists were on the verge of ousting the warlords who had controlled the city for 15 years. Two of her cousins were killed by mortars.
"I felt we just had to leave to escape the bullets and the war, and coming here was the only way to look after my family," she says.
Ms. Hassan left her husband in Mogadishu and walked with her three young daughters for 20 miles before finding a ride on a truck heading south to the Kenyan border.
The Islamists have been accused by the US of harboring Al Qaeda operatives, but closer to home they are credited with bringing peace to Mogadishu for the first time in years.
Many of the refugees tell a different story.
Aid workers say the arrivals are dominated by women and children running from violence, as well as boys and young men who fear being drafted into opposing militias.
Mohammed Qazilbash, senior program manager for CARE, the Atlanta-based aid agency that manages the camp, says: "The families that we see arriving are often in quite dire circumstances in terms of both a health and from a nutritional point of view, as well as from a trauma perspective."
He is dealing with a worst-case scenario of 100,000 new arrivals this year in a camp already home to 136,000 refugees.
More likely, he says, is that a total of 50,000 will find their way to Dadaab's stick-built shelters – a 20-fold increase in the 2,500 arrivals last year.
Rations reduced to cope with influx
Rations have been reduced by almost 10 percent to cope with the influx, and no one is sure how long the wells will continue to provide enough water, creating a "crisis waiting to explode," according to Mr. Qazilbash.
The three sub-camps that make up Dadaab were founded in 1991. The collapse of Siad Barre's brutal government and Somalia's descent into civil war sent the first refugees fleeing into Kenya's barren northern desert, where little more than thorn bushes and bandits can survive.
Aid vehicles travel only with police escorts, and, at night, humanitarian workers retire to compounds protected by razor wire.
The refugees leave behind a country on the brink of war.
The transitional government is not functioning while Prime Minister Ali Mohamed Gedi attempts to build a new Cabinet. President Abdullahi Yusuf dissolved the Cabinet last week following the recent resignation of 40 full and junior ministers. Peace talks scheduled for this week in Sudan's capital, Khartoum, look increasingly unlikely to take place.
And an already volatile situation has been inflamed by the presence of Ethiopian troops on Somali soil where they have been deployed to defend the fragile government.
A Western diplomat in Nairobi, speaking on condition of anonymity, says the result is a tense standoff.
"All three parties would love a fight, but all three parties dare not risk it for the moment," he says.
The Ethiopian troops know that any aggression against the Islamists might unite Somalia's warring clans against a common enemy. Most Somalians have a deep distrust for neighboring Ethiopia, which they see as an expansionist nation that still occupies a part of its territory.
The fragile transitional government knows it lacks the firepower to tackle the Islamists, who have proved to be an adept fighting force.
And the Islamists know that any attack on the transitional government would bring down Ethiopia's military might upon them.
Meanwhile, the Islamists have been consolidating their power and expanding the territory they control. They now control wide swaths of the country's south. Earlier this week, they took the port of Harardhere, some 185 miles north of Mogadishu, and every day there are reports of clan-based militias joining their ranks.
Tueday, Islamic militiamen reportedly advanced to Bur Haqaba, a town close to the transitional government's base in Baidoa.
The last time Islamists captured this town, on July 19, troops from Ethiopia crossed into Somalia the following day, prompting the Islamists to withdraw quickly.
With the future of their country hanging in the balance, few refugees have any thought of returning.
"I will be here for as long as the refugee camps are here," says Hassan quietly, as she sits on a reed mat.
The garbage-strewn camps have outlived 14 attempts to find peace in Somalia. No one is expecting them to close any time soon.