The worst storms in a decade left swathes of Israel and Jordan under a blanket of snow and parts of Lebanon blacked out on Thursday, bringing misery to a region accustomed to temperate climates.

Freezing temperatures and floods since Sunday have claimed at least 11 lives across the region and exacerbated the plight of hundreds of thousands of Syrian refugees huddled in tented camps in Jordan, Turkey and Lebanon.

The United Nations issued an urgent appeal for funds to help refugees in the northern Jordanian camp of Zaatari, which was almost entirely flooded on Wednesday, with residents battling mud and sub-zero temperatures.

"The next 72 hours will be a critical test of our ability to meet the basic needs of children and their families at Zaatari," UN Children's Fund (UNICEF) Jordan representative, Dominique Hyde said in a statement on Thursday.

The education ministry in war-hit Syria announced mid-term exams postponed until further notice as snow blanketed Damascus.

Students in other countries also got a break as authorities ordered schools and universities closed in Lebanon, Syria, Jordan and Israel and some towns in Iraqi Kurdistan.

In Jordan, a blizzard brought the country to a near halt. King Abdullah II ordered the army to help clear roads across the usually parched nation and help those stranded by the snow. Thursday was also declared a holiday.

The storm triggered power blackouts in several countries including Lebanon, where electricity has been rationed since the 1975-1990 civil war. Several areas were plunged into darkness, leaving those who rely on electricity to heat their homes shivering.

"Our boiler works with electricity, so of course we have no hot water," said Elsa, a Beirut housewife.

Officials and residents blamed the outage on the storm and an open-ended strike by employees of the state-run Electricite du Liban power company over salaries and pension issues.

Energy and Water Minister Gebran Bassil told AFP: "There is a storm, and there is a problem in the grid. The electricity workers are on strike, and they're not letting anyone fix the problem."

A Beirut international airport weather expert said the storm was the worst ever to hit Lebanon, while other met officials in the region said it was the worst in 10 years.

Media reports said the cold weather originated in Russia, with one daily dubbing the storm "Olga," and authorities urged citizens to remain indoors.

In Jerusalem, at least 10 centimetres (four inches) of snow blanketed the Holy City by dawn, turning the pine-covered hills into what looked like an Alpine ski resort picture postcard.

In the West Bank town of Ramallah, young and old alike rushed outside to make snowmen and engage in snowball fights.

But at least 11 people have reportedly died in the region because of the weather.

Among them were a man who froze to death after he fell asleep drunk in his car in Lebanon's eastern Bekaa Valley and a baby swept away in a flash flood in the centre of the country.

In the Palestinian territories, officials reported five fatalities since Tuesday, including a West Bank woman who died from a fire she started in her home to keep warm.

The storm also crippled many businesses, took a heavy toll on regional economies and, in Israel, put on hold campaigning for the January 22 general election.

The Manufacturers Association of Israel said the storm looked set to cost industry at least 300 million shekels ($80 million/60 million euros) in damage, most of it from flooding.

Three days of driving rain and strong winds that struck normally warm Egypt paralysed activity, including in most ports, with the commercial harbour in Alexandria on the Mediterranean sea worst affected, officials said.

Snowfall in the normally arid Sinai Peninsula was blamed for an accident in which four French tourists were slightly injured.

Snow even capped the northwestern Tabuk region of the desert kingdom of Saudi Arabia, where roads leading to Mount Alluz were packed with motorists excited at the sight of rare snow.

burs/srm