The strongest heat wave of the year so far continues sweeping across China as the country is expected to experience worse climate conditions and more extreme weather events in July and August, national weather forecasters said.

For the next week, the temperature is estimated to jump to 40 C in most parts of China, the National Meteorological Center said.

On Friday, the China Meteorological Administration launched a national Level IV emergency response to high temperature, the lowest grade of the response.

Southwest China's Sichuan province was among the areas hit hardest by temperatures that reached around 40 C.

The provincial government released an "urgent notice" on hot weather prevention on Friday.

The notice said that companies should give out high temperature subsidies and set flexible working hours for outdoor workers.

Authorities also need to prevent too much electricity usage on the network to keep away from a potential risk of fire.

On Friday, Shaanxi's Weinan meteorological service issued a red warning for high temperatures of above 40 C, the highest warning level in the local four-tier system.

Zhang Juan, a weather analyst at Weather China, a website under the administration, said this round of high temperatures has affected more than 20 provinces as the heat wave moves from western regions to the east.

The number of heat waves-periods with temperatures above 35 C-in East, Central and parts of South China as well as the Xinjiang Uygur autonomous region, will be above normal, according to a forecast released by the National Climate Center on Tuesday.