By the afternoon, the last place you want to be in Cairo is out in the street in temperature usually higher than 35°C. Yet for the hundreds of protesters camping in tents in Tahrir Square, that is exactly where they feel they have to be - the heat less of a concern than their worry over the current state of the Egyptian revolution.
Tahrir is again a campsite. Tents have been set up under large billowing makeshift white canopies. The mood is exuberant. The young men and women appear happy to be together again confronting a common enemy.
Six months after the Egyptian people surprised both themselves and the world by forcing Hosni Mubarak out of office, the protesters say it feels as if the Mubarak regime, apart from a few high profile symbolic scapegoats, is still in power. As the novelist Alaa Al Aswany wrote in an editorial in Al Masry Al Youm: "The generals of the Egyptian police who helped Habib Al Adly [the former interior minister] humiliate the Egyptians and torture them still hold their positions. The media officials who misinformed the public and fraudulently praised the dictator and justified his crimes still hold theirs.
"The judges who oversaw the rigging of the elections are still active. Even the state security officers who committed atrocious crimes have not lost their jobs, and some were even appointed governors."
The last time I met Sherif Azer, the secretary general of the Egyptian Organisation for Human Rights, was more than a year ago when the idea of protesters setting up an activist camp in the middle of Cairo would have seemed like the wildest fantasy. Talking to him in the middle of the square yesterday, I assumed that the life of a human rights activist must have improved - but he told me that since the revolution he had been beaten by the army and arrested, while his friends were being tried in military court.
At least 5,000 Egyptians have been put on trial in military tribunals since February. And the number of policemen convicted of the murder of almost 900 people during the revolution? One - and he was tried in absentia.
This time protesters say they are not leaving Tahrir until their demands are met. But what exactly are those demands? Last time the revolution had a focal point: the removal of Mr Mubarak. This time it's more nebulous: the people want justice and freedom, but now some are also asking for the removal of the people who are effectively running the country, the Supreme Council of the Armed Forces.
Much was made earlier this year about the Egyptian people's approval of the army; after all, one of last January's most celebrated chants was: "The people and the army are one." That now seems a long time ago.
Major General Mohsen El Fangari, the spokesman for the ruling council who became famous during the revolution for saluting the sacrifice of martyrs killed in the uprising, appeared on television two days ago. In a loud, finger-pointing speech, he told protesters to stop misbehaving and warned of a potential crackdown.
This time, though, some people laughed - one blogger, Sarah Carr, dubbed him "General Fingery" and in a satirical "translation" of his speech had him saying: "Since the beginning of the revolution the Supreme Council of Armed Forces has made clear that it is on the side of the people, mostly by locking them up after military trials and killing them in public squares."
The army is not used to being mocked; the question is how it will respond. In a press conference across town later that day, it made more conciliatory noises, saluting the Egyptian people and praising the revolution. But the generals still made it clear that they would take action if the protesters continued to block what was described as the functioning of the state.
What action would be taken remained unspoken. The army has promised that it will not use force against the demonstrators as long as they follow the law. But what if it is decided that the protesters are, in fact, breaking the law?
Outside Tahrir, among businessmen and women, street vendors, taxi drivers and the people who make their income from tourists (who are as scarce on Cairo's streets as people wearing pro-Mubarak T-shirts), there is a sense that the majority of people share the army's frustration with the protesters. They may support the protesters' goals but they are ready to wait for the elections, and ready to give the army a chance to make good on its promises.
The constant refrain is that if people are dissatisfied with the elections, then they will go back to the square. People are more worried about the dismal state of the economy, the high price of food and the struggle to find jobs. And they're upset by the images that the renewed protests send to the rest of the world, which has only recently started thinking of Egypt as a holiday destination again.
The problem for the protesters is that if the army does take action, and as long as that action is not too violent, it may have the tacit support of the majority.
Simon Mars is a television producer based in Dubai and London