Scenic spots offering cooler weather are seeing a surge in visitors, as people across northern China look to escape the current heat wave.

In the Xinjiang Uygur autonomous region, where temperatures have risen as high as 47 C, many are heading to Nanshan, a vast pasture about 55 kilometers south of Urumqi.

The area, with its forests, grasslands glaciers and low cost - just 20 yuan ($3) to get in - received about 30,000 visitors last weekend, website Xinjiangnet reported, citing the park's managing committee.

"With all the mountains, lakes and forests, it's really cool and comfy here, much better than sitting in an air-conditioned home," Wang Xue, who took her family to the park on Sunday, told the website.

People are also hiding from the heat in karaoke venues, shopping malls and parks.

Gao Guangling, 63, took her 18-month-old grandson to cool off at a riverside park in Beijing's Chaoyang district on Tuesday.

"Staying too long in an air-conditioned environment will definitely harm a person's health, especially young children," she said. "The shade provided by the trees here provides natural cooling."

Meanwhile, people in some cities are having to book KTV rooms up to two days in advance because of a spike in demand.

"I feel composed with the cool temperature in a karaoke venue, even if there's a long line ahead of me to use the rooms," Guo Nannan, a KTV customer in Urumqi, was quoted as saying by Xinjiangnet.

The National Meteorological Center issued an orange alert on Wednesday, the middle level in a three-tier warning system for heat. That followed two yellow alerts in the previous two days.

The center said 12 provinces, regions and municipalities, most in Northwest, North and East China, saw the temperature rise to between 37 C and 39 C on Wednesday.

In Shaanxi province and the Ningxia Hui autonomous region, local meteorological authorities have issued red alerts since Tuesday, the highest level in the warning system, with the mercury hitting 40 C.

The heat wave is expected to continue, and doctors are warning of the risk of sunstroke, which can be life-threatening.

"We've seen a sharp increase in the number of patients with sunstroke. Today alone we received two such patients in very serious condition," said Gu Chendong, deputy director of the emergency department at China-Japan Friendship Hospital, on Tuesday.

He suggested people cut the time they spend outdoors during the hottest hours, usually 10 am to 3 pm - especially the elderly and children.

Li Lei contributed to this story.