May was cooler and drier than usual with a mean temperature of 25.3 degrees Celsius, 0.5 degrees below normal. The Hong Kong Observatory recorded 191.9mm of rain, 137.6mm below normal. Accumulated rainfall since January 1 was 564.9mm, 15% below normal.

Under the influence of an easterly airstream, May 1 to 4 saw cloudy weather with mist and showers. A trough of low pressure over south China brought thundery showers May 5. The weather was cloudy with rain patches for the next two days.

A humid maritime airstream brought coastal fog May 8. It was sunny and hot May 9, and a northeast monsoon behind a cold front brought cooler weather for the next two days.

Fine and dry weather was brought by a dry northeast monsoon May 12 to 17. The weather turned cloudy with rain May 18 to 22 under the influence of a low-pressure trough. 

A southwesterly airstream brough hot weather with sunny periods May 23, with the maximum temperature of 31.4 degrees, the highest of the month.

The weather turned cloudier and more showery May 24 to 28, and a low pressure trough brought rainy and thundery weather May 29 to 31.