The Hong Kong Observatory issued its first "very hot weather" warning of the year yesterday, with temperatures surpassing 34 degrees Celsius in Sai Kung.
The warning was issued at 11.45am and was cancelled at 5.30pm.
Apart from Sai Kung, which recorded a maximum temperature at 34.7 degrees Celsius, Sheung Shui and Yuen Long Park also saw temperature rise to 34.4 degrees.
The Observatory also recorded a high temperature of 33 degrees at its headquarters in Tsim Sha Tsui.
The Observatory reminds the public to stay hydrated by drinking more water and avoid overexertion under the hot weather to prevent heatstroke.
However, people are reminded to carry umbrellas when going out today as the weatherman forecasted rain and thunderstorms that arrived last night and will continue to affect the city this morning.
"A trough of low pressure will move across the coast of Guangdong and bring thundery showers to the region tomorrow morning [Tuesday]," the Observatory said.
Weather today will be mainly cloudy with a few showers and rain will be heavier with squally thunderstorms in the morning. Showers will lessen gradually later in the day. Temperatures will range between 24 and 29 degrees Celsius.
Temperatures are expected to rise back to 30 degrees on Thursday. People will see sunshine again from Thursday to early next week. "Under the influence of an anticyclone aloft, the weather will improve and it will be hot over the coast of Guangdong in the middle and latter parts of this week," the Observatory said.
But the weatherman forecasted that very hot weather will appear again early next week with temperature climbing to 33 degrees next Monday and Tuesday.
The Observatory said the very hot weather is an impact from tropical cyclone Mawar, which is now over the western North Pacific and will move towards the seas east of the Philippines later this week. "Under the influence of its outer subsiding air, it will be very hot over Guangdong early next week."
Although it's unlikely for Mawar to hit Hong Kong and its route remains uncertain at this stage, people travelling to Taiwan and Japan have to pay attention to the weather forecast.
The weather bureau in Taiwan predicts that the typhoon may move near the southern part of the island early next week, while an alternative route could be that Mawar could turn north and hit Japan.