And Mr Guterres's cabinet of relative lightweights cannot rely on an outright majority in parliament.
Mr Guterres also called on all European countries to work more effectively together to standardise their asylum policies.
High Commissioner Antonio Guterres said the numbers - and particularly the rapid escalation during August - are worrying.
BBC: Syria envoy Lakhdar Brahimi warns of 'staggering' crisis
Mr Guterres has only narrowly escaped a formal reprimand of the kind recently meted out to the Irish.
To a large extent, it is Mr Guterres himself who is to blame for this year's spending excesses.
This in turn prompted a wider reshuffle which Mr Guterres had wanted to delay until after the local elections.
More people will move from one country to another, because they want to or because they are forced to, Guterres said.
High Commissioner for Refugees Antonio Guterres in April, accompanied Guterres on a visit to the Kilis camp in Turkey on Thursday.
CNN: U.N. envoy Angelina Jolie visits Syria refugees in Iraq
One of Mr Guterres's advisers explains that it all goes back to the period after the election in October last year.
Portugal has avoided the unrest over petrol prices seen in Britain and France this autumn, because Mr Guterres yielded without a fight.
These days, Portugal's Socialist prime minister, Antonio Guterres, cuts more of a dash abroad than his conservative counterpart in Spain, Jose Maria Aznar.
ECONOMIST: Spain and Portugal: Ever closer, inside Europe’s Union? | The
The influx of Syrian refugees strains the nearby countries, Guterres said.
CNN: U.N.: Number of Syrian refugees escalating at rapid rate
"The refugee crisis has been accelerating since last summer, and has reached staggering proportions since the beginning of this year, " Guterres told a Senate Foreign Relations subcommittee.
So, with Mr Vitorino on his way, it would have been odd if Mr Guterres had not taken the opportunity to give his cabinet a new look.
Though the period of goodwill that followed the Socialists' return to government after a decade in opposition is over, Mr Guterres has a fair bit to boast about.
In 2012, the UN's High Commissioner for Refugees, Antonio Guterres, said that a "criminal network" of smugglers and traffickers was "taking profit of the desperate situation of many Eritreans".
The number of refugees arriving in neighboring countries has jumped to 14, 000 in a 24-hour period, up from 3, 000 in December, 5, 000 in January and 8, 000 in February, Guterres said.
The downfall of the defence minister, Antonio Vitorino, one of Mr Guterres's closest colleagues, was largely a consequence of the prime minister's own zeal in tackling tax evasion and sleaze.
My next time in the corner (yes, there are some comfortable chairs nearby), I talked with Antonio Guterres, the UN High Commissioner for Refugees and the former prime minister of Portugal.
The root of the problem is that public spending has been rising steadily since Mr Guterres took office in 1995: remarkably, he has managed to add 50, 000 people to the public-sector payroll, now 680, 000-strong.
The UN High Commission for Refugees, Antonio Guterres, who visited the camp on Thursday, said it was through solving conflict in Somalia and bringing aid to Somalia itself that the crisis here could be mitigated.
The Portuguese Prime Minister, Antonio Guterres, said on Saturday he could no longer "be completely confident" in Nato assurances, while Poland has announced plans to carry out medical tests to all its soldiers in Kosovo.
The same pollsters who give him such a hard time, he says, got it badly wrong last year: they had forecast, shortly before the general election, that Mr Guterres would win a bigger majority than Mr Cavaco Silva had held.
应用推荐