SHENYANG, July 31 (Xinhua) -- A heat wave is sweeping most parts of China, with several regions issuing alerts for high temperatures.

A vast area of China, including Liaoning, Jilin, Chongqing, Hubei, Xinjiang and Inner Mongolia, saw temperatures between 37 and 39 degrees Celsius, according to the National Meteorological Center on Tuesday (NMC).

Tuesday was the 18th consecutive day that the NMC renewed a yellow alert for high temperatures.

In northeastern province of Liaoning, where people are used to cool summer days, the top subject discussed online has been when the scorching heat will end. Liaoning's meteorological disaster monitoring center issued an orange alert for heat wave on Tuesday morning.

Watermelons and ice cream have become daily necessities. Meanwhile, sales of air conditioners have soared.

"There are about 8,000 air conditioners waiting to be installed and new installation orders will be placed after five days," said a salesman in Shenyang Zhongjie commercial district.

Traffic police officer Gao Ying said she has used up one whole bottle of sunblock in just 10 days.

Experts with Liaoning Meteorological Society explained that Western Pacific subtropical high moved northward too early at higher latitude this month to cause unusual high temperatures in the northeast, and even influenced the weather in Russia and some Nordic countries.

According to the NMC, the heat wave is likely to continue in the northeast and the north until August 6.

People should reduce their outdoor activities, and local authorities should take precautions against fires caused by excessive power loads, the center said.

China has a three-tier, color-coded warning system for heat waves, with red representing the most severe, followed by orange and yellow.