Chongqing Municipality in southwest China issued a red alert on Thursday for high temperatures, the highest level in the country's high-temperature alert system.

Thirty districts and counties in Chongqing are expected to see temperatures surpass 40 degrees Celsius between 1 p.m. and 7 p.m. Thursday, according to the Chongqing Meteorological Service.

The meteorological department has advised people in these areas to guard against fires and to reduce outdoor activities.

Chongqing has been enduring a heat wave since earlier this week, with orange alerts, the second-highest level for high temperatures, issued for Tuesday and Wednesday.

Red is the highest level in China's three-tier high-temperature alert system, followed by orange and yellow. A red alert is issued when temperatures are forecast to exceed 40 degrees Celsius within 24 hours.

The megacity of Chongqing is dubbed the "furnace city" due to its scorching summers.