September was hotter and wetter than usual with 10 days recording maximum temperatures of 33 degrees Celsius or above, breaking the records for 1963 and 1969, the Hong Kong Observatory says.

The mean temperature was 28.8 degrees, 1.2 degrees above normal. The mean minimum temperature of 26.9 degrees was also the highest on record for September.

Total rainfall of 486.3mm was 69% above normal. Accumulated rainfall since January 1 was 2,027.3mm, about 6% below normal.

Affected by a ridge of high pressure over southern China the local weather was fine and very hot for the first eight days of the month but became cloudy with showers on September 9 due to an easterly airstream.

An area of low pressure intensified into a tropical storm named Mujigae on September 10. Local winds strengthened gradually with some scattered squally showers. Due to the storm's outer rainbands, the weather remained cloudy with occasional rain September 11. The rain eased off while Mujigae made landfall over northern Vietnam and weakened the next day.

A tropical depression entered the northern part of the South China Sea September 13 and intensified into tropical storm Koppu that evening. Its outer rainbands brought a few thundery showers and Koppu intensified into a typhoon September 14, bringing cloudy weather with squally showers and strong winds. Gale force southeasterly winds with maximum gusts up to 151kph were recorded in the late evening.

Koppu made landfall over the western Guangdong coast September 15 and weakened into a tropical storm. Its rainbands brought heavy squally showers to the city that day. With Koppu moving further inland and dissipating the showers eased off gradually on September 16.

A ridge of high pressure brought generally fine weather September 17 to 20. A cold front crossed the coastal areas of Guangdong September 21, bringing a few thundery showers to Hong Kong. The northeast monsoon behind the cold front brought generally fine weather September 22 to 27.

Tropical Storm Ketsana entered the South China Sea September 26 and intensified into a severe tropical storm the next day. Under the combined effect of Ketsana and the northeast monsoon local weather was windy with rain September 28 and 29. After Ketsana made landfall the weather was rainy on the last day of the month.