On July 30, China's meteorological authority issued the country's first Grade 2 alert - the second most serious weather alert in the four-tier ranking system - as the record-breaking heat wave engulfed areas in east and southwest China.

The soaring temperatures showed no signs of easing in Shanghai and the neighboring provinces of Zhejiang, Jiangsu and Anhui and the southwestern city of Chongqing. Temperatures in these areas could still cross 40 degrees Celsius, the National Meteorological Center said yesterday.

For the fourth straight day yesterday, the center issued the orange high-temperature alert, or the second highest in the three-color category, which includes red and yellow. Red denotes temperatures could rise above 40, and yellow is for temperatures between 35 and 37.

The Grade 2 alert was the highest heat wave alert since China came up with the National Meteorological Disasters Emergency Plan in 2010. It was issued only after two provincial areas recorded high temperatures of 37 degrees in the previous two days and with no change in the weather pattern expected in the next two days.

The emergency plan has four levels of disastrous alerts. Grade 2, or the second highest level, implies 'serious disastrous weather.' The top level signifies 'specially severe.'

'The weather authorities in the worst-hit areas like Shanghai, Anhui and Jiangsu should adopt the emergency mode and report to the administration, issue high temperature alerts and update the weather reports to the public in time,' the state meteorological administration said.

Under the Grade 2 alert, weather authorities are inclined to increase the frequency of weather forecasts and reports. Power and water suppliers must ensure residential usage remains unaffected.

Among other regions and cities battling hot weather, Henan, Hebei, Guangdong, Guangxi, Guizhou, Sichuan and Beijing will see temperatures above 35 degrees, the center said.