The Observatory recorded this year's highest temperature at 37.4 degrees Celsius in Sheung Shui yesterday, with its Tsim Sha Tsui headquarters recording 35.1 degrees in the afternoon.
An average reading of over 33 degrees was recorded in most parts of the city.
The Observatory recorded the highest temperature in Sheung Shui around 3.20pm.
Temperatures in Wong Tai Sin also climbed to 36.3 degrees in the afternoon.
In Ta Kwu Ling, Tai Lung, Shek Kong, Yuen Long Park and Happy Valley, the Observatory recorded a temperature of 35 degrees or above, while Tai Mei Tuk, Wetland Park in Yuen Long, Tai Po, Sha Tin, Tsuen Wan Shing Mun Valley, Kowloon City, Sham Shui Po, Tseung Kwan O, and Chek Lap Kok also saw highs of 34 degrees or above.
Very hot temperatures are expected to persist over the next few days, touching a maximum of around 34 to 35 degrees.
"An anticyclone aloft will bring fine and very hot weather to southern China in the next couple of days," the Observatory said.
It will be very hot during the day today, with temperatures ranging from 28 to 35 degrees.
Tomorrow's weather is expected to be very hot and mainly fine but with isolated showers. Temperatures will range from 28 to 34 degrees.
In view of the very hot weather, the Centre for Health Protection reminded people to take precautions against heat stroke and sunburn, especially when undertaking outdoor activities.
"Drink plenty of water to prevent dehydration while engaging in outdoor activities," a CHP spokesman said, adding children, elderly, the obese and those with chronic illnesses should pay special attention.