May saw a mean temperature of 25.6 degrees Celsius, close to the 25.8-degree normal figure, with a highly uneven rainfall distribution, the Hong Kong Observatory says.

Total rainfall in the month was 176.6mm, 54% of the normal figure, while more than 400mm and 300mm of rainfall were recorded in the eastern part of the New Territories and western Lantau. The accumulated rainfall so far this year was 410.7mm, about 38% below normal.

Due to a ridge of high pressure, the city was generally fine for the first three days of the month. An easterly airstream brought mist and light rain patches over the next two days.

Affected by a trough of low pressure, the weather became cloudy with showers on May 6 and deteriorated further with heavy rain and squally thunderstorms May 7.   Dominated by a humid maritime airstream, it was mainly cloudy with coastal fog on May 8.

There were some showers the next day. Due to a low-pressure system, it was stormy on May 10. Local weather improved with some sunny intervals May 11 to 13 with the establishment of a weak ridge of high pressure. Affected by a humid easterly airstream, there were a few light rain and fog patches on May 14.

Another trough of low pressure brought thundery showers the next day. The weather became mainly cloudy with a few rain patches and coastal mist on May 16 and 17 due to an easterly airstream. It was fine and hot on May 18, but because of a low-pressure system, it turned rainy with a few squally thunderstorms for the ensuing two days.

A moist maritime airstream brought hot weather to Hong Kong on May 21, with the temperature rising to a maximum of 30.7 degrees, the highest of the month. The weather became cloudy with some showers and thunderstorms on May 22 and 23 before a dry continental airstream brought fine and dry conditions for the next three days.

Dominated by an easterly airstream, local weather turned mainly cloudy with a few rain patches on May 27. While there were some sunny periods on May 28, there was an episode of thundery showers on May 29 evening. The weather remained showery with squally thunderstorms the next day, with more than 100mm of rain recorded in Sha Tin and Sai Kung that afternoon. There were still a few rain patches on the last day of the month.