"Extreme weather and climate change impacts across Asia in 2020 caused the loss of life of thousands of people, displaced millions of others and cost hundreds of billions of dollars, while wreaking a heavy toll on infrastructure and ecosystems," the WMO said.
"Sustainable development is threatened, with food and water insecurity, health risks and environmental degradation on the rise."
The report comes days before COP26, the UN Climate Change Conference being held in Glasgow from Sunday to November 12.
The report also laid bare the total annual average losses due to climate-related hazards.
China suffered an estimated $238 billion, followed by India at $87 billion, Japan with $83 billion and South Korea on $24 billion.
But when the size of the economy is considered, the average annual losses are expected to be as high as 7.9 percent of gross domestic product for Tajikistan, 5.9 percent for Cambodia and 5.8 percent for Laos.
Increased heat and humidity are forecast to lead to an effective loss of outdoor working hours across the continent, with a potential cost of many billions of dollars.
"Weather and climate hazards, especially floods, storms, and droughts, had significant impacts in many countries of the region," said WMO chief Petteri Taalas.
"Combined, these impacts take a significant toll on long-term sustainable development."
Many weather and climate-related displacements in Asia are prolonged, with people unable to return home or integrate locally, the report said.
In 2020 floods and storms affected approximately 50 million people in Asia, resulting in more than 5,000 fatalities.
This is below the annual average of the last two decades (158 million people affected and about 15,500 fatalities) "and is testimony to the success of early warning systems in many countries in Asia", with around seven in 10 people covered.
Asia's warmest year on record saw the mean temperature 1.39 degrees Celsius above the 1981–2010 average.
The 38.0 C registered at Verkhoyansk in Russia is provisionally the highest known temperature anywhere north of the Arctic Circle.
In 2020, average sea surface temperatures reached record high values in the Indian, Pacific and Arctic Oceans.
Sea surface temperatures and ocean warming in and around Asia are increasing more than the global average.
They have been warming at more than triple the average in the Arabian sea, and parts of the Arctic Ocean.
Arctic sea ice minimum extent (after the summer melt) in 2020 was the second lowest on the satellite record since 1979.
