The observatory on Monday said it had recorded the city's hottest day so far this year, with the mercury hitting 35.4 degrees Celsius at its headquarters in Tsim Sha Tsui.

This topped the year's previous high of 34.8 degrees on July 7.

Other parts of the territory were even hotter on Monday afternoon, with 37.3 degrees recorded in Happy Valley, 37.7 degrees in Yuen Long Park and 38.9 degrees in Sheung Shui.

Scientific Officer Sin Chuen-keung warned that further extremely high temperatures are expected in the coming week.