Meanwhile, the Meteorological Department reported the hottest day this year in Muang district of Tak on Monday when the mercury hit 43.2 degrees Celsius. That is short of the hottest temperature of 44.5 degrees recorded in Uttaradit in 1960.

Bangkok residents are sweltering in heat between 37 and 39 degrees Celsius. The weather office warned of thunderstorms between now and tomorrow.

Bannasophit said Bangkok had contributed to global warming with emissions of greenhouse gasses and consumption of resources. It is among the worst offenders in Southeast Asian.

Bangkok Governor Apirak Kosayodhin wants experts to formulate guidelines to lower consumption and emissions as well as raise public awareness of climate change. He will meet them next week.

The Southeast Asia director of System for Analysis Research and Training (START) based at Chulalongkorn University, Dr Anon Sanitwong na Ayutthaya, said he had spoken to Apirak about reducing Bangkok's impact on global warming.

He will work on a 10-point plan including more green areas, pollution solutions and energy-saving measures. Anon said START was improving its climate modelling for Thailand that had already predicted the country will swelter in 33-degree-plus heat for as many as 60 days a year in 30 years to 80 years hence.

The new model will provide an even more accurate prediction of temperature rise, he said.

START adviser Dr Jariya Boonyawat said studies into global warming and its effects on humans found increasing populations, economic development, deforestation and growing industrialisation caused climate change.

With Thailand currently experiencing temperatures well into the 40s - from a historical average April high of 34 - she predicted 2008 would be even warmer.

As surface temperatures increase, hot air rises heating clouds that then collide with cooler air in the upper atmosphere. This produces instability, she said. That can lead to violent storms and hailstorms. Jariya called for more research into the phenomenon.