Canada witnessed an all-time high temperature of 49.5 degrees Celsius (116-degree Farhenheit) on June 29 in Lytton, British Columbia. The town, which is about 150 miles (250km) north-east of Vancouver, had been experiencing high temperatures for the three days, as per Lytton climate station.

More than 40 spots in British Columbia set new temperature records. Citizens said that parts of western Canada were hotter than Dubai.

At least 233 deaths were recorded in Canada between June 25 and 28, officials said.

The 'heat dome' broke an 84-year-old record when two towns in Saskatchewan -- Yellow Grass and Midale – sizzled at 45°C (113°F) in July 1937, as per officials from Lytton climate station.

Cooling shelters have come up all over and the sale of air-conditioners and fans has jumped in the last few days.

BBC's weather forecaster Nick Miller says that ‘heat dome’ describes huge areas of high pressure resulting in clear skies and hot sunny days. Temperatures can build day by day as the high-pressure pattern continues.

This time, the high-pressure area stretches from California to Canada's Arctic regions and inland through Idaho, officials said. The heatwave gripped Canada's western and the US Pacific northwest, media agency AFP reported.

Calling the heatwave conditions "historic", the US National Weather Service said that areas in the Pacific north-west have also been breaking records, particularly in parts of Washington and Oregon states.

Experts say that the frequency of extreme climatic occurrences such as heatwaves is increasing due to global warming.

India's capital New Delhi witnessed its first severe heat wave of 2021 on June 29 with Safdarjung Observatory recording a maximum temperature of 43°C, said PTI.

The India Meteorological Department (IMD) said a “severe” heat wave is declared if the normal temperature rises more than 6.5°C.