In Portugal and Spain huge wildfires in recent weeks have forced thousands from their homes and reduced large swathes of land to ashes. Though the fires are now under control, there are fears they could flare again, with more hot weather forecast.

The European Forest Fire Information System said there have been 391 wildfires in Spain this year, laying waste to a total of more than 283,000 hectares of land, more than three times the area consumed by wildfires in the whole of last year.

Record high temperatures have also hit many parts of the United States this summer, much of the western US enduring an unrelenting drought.

A recent study by the climate research group First Street Foundation said that more than 100 million US people are expected to experience extremely dangerous heat exceeding 52 C in just 30 years, with both the intensity and frequency of the hottest days of the year rising.

On Wednesday the city of Yangon in Myanmar encountered the heaviest single-day rainfalls in more than 50 years, the Department of Meteorology and Hydrology said. Yangon recorded 170 mm of rain in one day.

In Pakistan more than 580 people have died and thousands have lost their homes due to torrential rains recently. Since last month it is estimated that about 1 million people have been affected by heavy rain, flash floods and landslides as the country had had more than 60 percent of its normal total monsoon rainfall in just three weeks.

In New Zealand, torrential rain hit parts of the country for a fourth day on Friday, forcing hundreds of people from their homes as rivers overflowed their banks and waterlogged ground became unstable.

In Algeria a string of forest blazes killed at least 38 people last week. Deadly fires have become prevalent in the country as climate change has turned large areas of forest into a tinderbox in the hot summer months.

In China the heat has affected southern parts of the country since June. The National Meteorological Center forecast that the duration of this year's regional high temperatures, which have yet to end, will break the 62-day record set in 2013, becoming the longest heat wave in 61 years.

Hu Bin, an associate researcher in the Institute of Climate Change and Sustainable Development of Tsinghua University, said extreme weather will be harmful economically, seriously curbing long-term economic growth of the countries affected. This may exacerbate inequality, Hu said.

In the US a White House document said that this year alone extreme weather has upended the US economy and affected 1 in 3 Americans.

"Both international and domestic supply chains have been disrupted by climate change … supply chains across critical industries including housing, construction, semiconductors, and agriculture have been affected, causing delays and shortages for both consumers and businesses."

Extreme weather has caused Americans $600 billion in damage over the past five years alone, it said, and climate-related risks hidden in workers' retirement plans have already cost US retirees billions in lost pension dollars.

"Climate change poses a systemic risk to our economy and our financial system, and we must take decisive action to mitigate its impacts," the report said.

Extreme weather events in Europe over the 40 years to 2020 such as heat waves and floods killed about 142,000 people and cost the continent almost 510 billion euros ($575.2 billion), a report by the European Environment Agency earlier this year said. The agency called for continued adaptation measures at both individual and state levels.