“The subtropical ridge is bringing very hot and generally fine weather to the coast of Guangdong,” it said.

“Locally, the maximum temperature recorded at the Observatory was 33 degrees in the afternoon, the highest so far this year.”

The Observatory warned the sizzling heat would continue over the next few days, while the region was also expected to see thunder and showers.

The record for the hottest day of the year may be smashed again over the weekend, when temperatures are expected to reach 34 degrees.

Over at the Observatory’s Sheung Shui weather station, the forecaster saw the mercury peak at 35 degrees on Thursday afternoon.

The Labour Department also sent out its second amber heat warning of the year at 9.50am. The alert was later cancelled at 4.50pm.

Authorities only issue an amber alert under the government’s three-tier warning system, which was introduced last year, when the heat index hits 30 degrees.

Under the department’s guidelines, anyone working outside is recommended to rest for between 15 and 45 minutes for every hour depending on the potential risks involved and heatstroke precautions taken by employers.

A red alert only goes out when the heat index reaches 32 degrees, while a black warning requires a reading of 34 degrees.