Heavy thunderstorms lashed the United Arab Emirates on Tuesday, dumping over a year and a half's worth of rain on the desert city-state of Dubai in the span of hours as it flooded out portions of major highways and its international airport.

Meanwhile, the death toll in separate heavy flooding in neighbouring Oman rose to 18 with others still missing as the sultanate prepared for the storm.

The rains began late Monday, soaking the sands and roadways of Dubai with some 20 millimetres (0.79 inches) of rain, according to meteorological data collected at Dubai International Airport. The storms intensified around 9 a.m. local Tuesday and continued throughout the day, dumping more rain and hail onto the overwhelmed city.

By the end of Tuesday, more than 142 millimetres (5.59 inches) of rainfall had soaked Dubai over 24 hours. An average year sees 94.7 millimetres (3.73 inches) of rain at Dubai International Airport, the world's busiest for international travel and a hub for the long-haul carrier Emirates.

At the airport, standing water lapped on taxiways as aircraft landed. The airport ended up halting arrivals Tuesday night and passengers struggled to reach terminals through the floodwater covering surrounding roads.

Police and emergency personnel drove slowly through the flooded streets of Dubai, their emergency lights shining across the darkened roads. Lightning flashed across the sky, occasionally touching the tip of the Burj Khalifa, the world's tallest building. The city's driverless Metro saw disruptions and flooded stations as well.

Schools across the UAE, a federation of seven sheikhdoms, largely shut ahead of the storm and government employees were largely working remotely if able. Many workers stayed home as well, though some ventured out, with the unfortunate stalling out their vehicles in deeper-than-expected water covering some roads.

Authorities sent tanker trucks out into the streets and highways to pump away the water. Water poured into some homes, forcing people to bail out their houses.

The country's hereditary rulers offered no overall damage information or injury information for the nation, as some slept into their flooded vehicles Tuesday night. In Ras al-Khaimah, the country's northernmost emirate, police said one 70-year-old man died when his vehicle was swept away by floodwater.

Fujairah, an emirate on the UAE's eastern coast, saw the heaviest rainfall on Tuesday with 145 millimetres (5.7 inches) falling there.

Authorities cancelled school and the government instituted remote work again for Wednesday.

Rain is unusual in the UAE, an arid, Arabian Peninsula nation, but occurs periodically during the cooler winter months. Many roads and other areas lack drainage given the lack of regular rainfall, causing flooding.

Rain also fell in Bahrain, Qatar and Saudi Arabia.

In neighbouring Oman, a sultanate that rests on the eastern edge of the Arabian Peninsula, at least 18 people had been killed in heavy rains in recent days, according to a statement on Tuesday from the country's National Committee for Emergency Management. That includes some 10 schoolchildren swept away in a vehicle with an adult, which saw condolences come into the country from rulers across the region.