Beijing on Friday upgraded its warning for hot weather to “red” — the highest in a colour-coded alert system — with many parts of the Chinese capital roasting in temperatures of up to 40 degrees Celsius.

The official temperature for the capital, which is measured from its southern suburbs observatory, hit 40C just after 1:30pm (5:30am GMT) on Friday, according to the Beijing Municipal Meteorological Observatory.

“This is the first time since the establishment of the observatory that there has been a high temperature of more than 40C for two consecutive days,” Zhang Yingxin, chief forecaster of the Municipal Meteorological Observatory, said at a press briefing. The observatory was founded in 1951.

On Thursday, the maximum temperature in the city of nearly 22 million people breached 41C and shattered the record for the hottest day in June.

A weather station in its southern suburbs, considered to be Beijing’s main gauge, recorded 41.1C in the afternoon. The previous June high was logged on June 10, 1961 when the mercury hit 40.6C.

The daily maximum logged on Thursday was the city’s second-highest in history, just below the 41.9C recorded by Beijing on July 24, 1999.

China has a four-tier weather warning system, with red being the most severe, followed by orange, yellow and blue. A red alert indicates the temperature is set to rise above 40C within 24 hours.

The China Meteorological Administration said on Thursday it expected high temperatures to persist across much of the country’s north for the next eight to ten days.

High-temperature monitoring and warnings would continue on a rolling basis in places including Beijing, Tianjin, Hebei, Shandong, Henan and Inner Mongolia, it added.

In Tianjin, a northern Chinese port city with a population of over 13 million, Thursday’s temperature reached 41.2C, smashing local records.

Local authorities on Friday warned the extended period of high temperatures could have health impacts — including an increased risk of stroke — and advised people to drink at least one and a half litres of water daily and limit their time outdoors.