Climate-risk analysing company XDI (Cross Dependency Initiative) issued the ranking in a report on risks to hospitals from flooding, coastal inundation, extreme wind, forest fire, cyclone and greenhouse gas emission.
The report showed that 16,245 of 200,216 hospitals worldwide could be at risk without a phase-out of fossil fuels.
Of them, 5,894 are in South Asia, followed by East Asia (3,216) and Southeast Asia (1,862). The top three at-risk countries are India (5,120), China (1,302) and Japan (1,145).
"All of these 16,245 hospitals will require adaptation, where suitable," the report said. "Even with this enormous investment, for many, relocation will be the only option."
In Southeast Asia, Indonesia has the highest number of hospitals at risk of total or partial shutdown (696) followed by the Philippines (550) and Vietnam (263).
Thailand was ranked fourth in the region with 104 hospitals at risk of total or partial shutdown.
Thailand's potential extreme-weather hazards include riverine flooding, coastal inundation and surface water flooding. The report also indicates that high greenhouse gas emissions could cause severe damage to 1,608 hospitals across Thailand.
"Hospitals located on coastlines and near rivers are most at risk due to riverine and surface water flooding," the report said.
"Towards the end of the century, coastal inundation will rapidly increase (exacerbated by sea-level rise) and become the most significant hazard after riverine flooding by 2100."
It added that limiting global warming to 1.8C with a rapid phase-out of fossil fuels would halve the damage risk to hospital infrastructure compared to a high-emissions scenario.