China issued its first national heat-health risk warning on Wednesday evening as the country braces for another wave of extreme temperatures.

The joint alert from the National Disease Control and Prevention Administration and the China Meteorological Administration aims to strengthen public health preparedness amid growing climate challenges.

The new warning system integrates weather forecasting with health risk management, offering the public early guidance to reduce the medical impacts of extreme heat. Updates will be broadcast on major channels, including the weather forecast on China Central Television, the meteorological administration said.

The latest alert, effective from 8 pm Wednesday to 8 pm Thursday, warns of elevated health risks in several regions. A yellow alert, indicating moderately high risk, was issued for parts of North China, the Huanghuai region, the northern Jiangnan region, and Inner Mongolia.

Parts of Jiangsu, Shandong, Henan, Anhui and Heilongjiang provinces are under an orange alert, signaling high risk. A red alert, the highest level, was issued for northeastern Jiangsu, eastern and central Shandong, eastern Henan, northern Anhui, and northeastern Heilongjiang.

Wang Qing, an expert with the disease control administration, said the human body's sweating system may fail under high temperatures, leading to illnesses such as heat rash and heatstroke. High temperatures can also exacerbate chronic diseases, including cardiovascular and respiratory conditions, Wang said.

Authorities urged the public to monitor local forecasts, avoid outdoor activities during peak heat hours, stay hydrated and limit exposure to high temperatures.

The new system classifies heat-health risks into five levels: low, moderate, moderately high, high and extremely high.

Li Yi, deputy chief of the meteorological administration's public service center, said unlike routine high-temperature warnings, the new system reflects the impact of extreme heat on health and is tied to disease risk. It is based on analysis of the correlation between heat exposure and excess mortality from cardiovascular and respiratory diseases.

Unlike previous alerts that relied on national temperature thresholds, the new grading system is tailored to regional vulnerabilities, Li said.

The heat-health warnings will be distributed through multiple channels, including SMS alerts from the national emergency platform, mobile apps and social media platforms such as Sina Weibo and Douyin, according to the administration.

Development of the system began in May last year. Using technology from the Chinese Center for Disease Control and Prevention, the meteorological service center analyzed historical data from 2,400 stations across the country over the past decade, expanding risk thresholds from 334 urban stations to more than 2,400 county-level stations, the administration said.