BEIJING, May 21 (Xinhua) -- Beijing's observatory issued a yellow alert on Tuesday for high temperatures over the next four days.

Temperature could rise to 35 degrees Celsius from Wednesday to Saturday, and reach up to 37 degrees Celsius on Thursday.

The observatory advised residents to guard against the hot weather, and workers who are exposed to high temperatures should take protective measures.

The temperature is expected to drop significantly on Sunday, the observatory said.

China has a four-tier color-coded weather warning system, with red representing the most severe weather, followed by orange, yellow and blue.