Appendix F Meteorological Data

November 2016

November 2016 was characterized by relatively warm weather during the first three weeks, followed by rainy and cooler weather in the latter part of the month. Overall, the month was warmer and much wetter than usual. The mean temperature for the month was 22.3 degrees, 0.5 degree above the normal figure of 21.8 degrees. The monthly total rainfall recorded at the Hong Kong Observatory was 131.3 millimetres, more than three times the November normal of 37.6 millimetres and the eighth highest on record for November. The accumulated rainfall of 3020.2 millimetres up to end of November was about 27 percent above the normal figure of 2371.7 millimetres for the same period.

December 2016

With the northeast monsoon over the south China coastal areas remaining relatively weak for most of the month, December 2016 was warmer than usual. The monthly mean temperature of 19.6 degrees was 1.7 degrees above the normal figure of 17.9 degrees and the third highest for December since record began in 1884. The total rainfall recorded in the month was only 6.6 millimetres, less than one quarter of the normal figure of 26.8 millimetres. But in terms of rainfall for the whole year, the annual total of 3026.8 millimetres was about 26 percent above the yearly normal of 2398.5 millimetres.

January 2017

With no significant cold surge affecting the coastal areas of Guangdong, January 2017 became the warmest January in Hong Kong with record-breaking monthly mean temperature of 18.5 degrees and monthly mean minimum temperature of 17.0 degrees, 2.2 degrees and 2.5 degrees above their respective normals. The month was drier than usual in terms of rainfall amount with only 7.8 millimetres in total, less than one-third of the normal of 24.7 millimetres for January.

February 2017

February 2017 was brighter than usual, with the duration of sunshine in the month more than 40 percent above normal. The month was also relatively mild with a mean temperature of 17.0 degrees, 0.2 degree above the normal of 16.8 degrees. The monthly total rainfall was 19.9 millimetres, less than half of the normal of 54.4 millimetres. The accumulated rainfall of 27.7 millimetres in the first two months of the year was about 65 percent below the normal of 78.9 millimetres for the same period.

March 2017

Going into a season of transition between the northeast monsoon and the mild and humid maritime airstream over the south China coast, local weather in March 2017 was marked by fluctuating temperatures. While the monthly mean temperature of 19.3 degrees was only 0.2 degree above the normal of 19.1 degrees, total rainfall in the month, 48.0 millimetres, was about 42 percent below the March normal of 82.2 millimetres. The accumulated rainfall of 75.7 millimetres in the first three months of the year was about 53 percent below the normal of 161.3 millimetres for the same period.

April 2017

April 2017 was warmer than usual with a mean temperature of 23.3 degrees, 0.7 degree above the normal of 22.6 degrees. The month was also drier than usual in terms of rainfall with 58.8 millimetres recorded in the month, only about one-third of the normal of 174.7 millimetres. The accumulated rainfall recorded in the first four months of the year was 134.5 millimetres, a deficit of 60 percent compared to the normal of 336.1 millimetres for the same period.

May 2017

Due to the heavy rain on the morning of 24 May, the month was wetter than usual. The total rainfall recorded in the month was 399.3 millimetres, about 31 percent above of the normal figure of 304.7 millimetres. The accumulated rainfall recorded in the first five months of the year was 533.8 millimetres, a deficit of about 17 percent compared to the normal figure of 640.8 millimetres for the same period.

June 2017

As a result of the very hot weather in early June and the rainy spell in mid-June, the month was overall warmer and wetter than usual. The monthly mean temperature was 28.8 degrees, 0.9 degree above the normal of 27.9 degrees. The total rainfall recorded in the month was 656.0 millimetres, about 44 percent above the June normal of 456.1 millimetres. The accumulated rainfall recorded in the first half year was 1189.8 millimetres, a surplus of 8 percent compared to the normal of 1096.9 millimetres for the same period.

July 2017

With a trough of low pressure lingering over the south China coastal region in the early part of the month and frequent tropical cyclone activities over the northern part of the South China Sea in the latter half, July 2017 was cloudier with more rain than usual. The monthly total rainfall was 570.0 millimetres, more than 50 percent above the normal figure of 376.5 millimetres. The accumulated rainfall recorded in the first seven months of the year was 1759.8 millimetres, nearly 20 percent above the normal figure of 1473.3 millimetres for the same period.

August 2017

August 2017 was hotter than normal and the prolonged heat was relieved by the successive strikes of tropical cyclones Hato and Pakhar within a 5-day period during the latter part of the month. Both cyclones led to the raising of Gale or Storm Signal No.8, with Hato even necessitating the issuance of the Hurricane Signal No.10 on 23 August, the first time since July 2012. The mean temperature recorded in the month was 29.3 degrees, the seventh highest for August on record and 0.7 degree above the August normal of 28.6 degrees. Due to the rain brought by Hato and in particular Pakhar, the monthly total rainfall amounted to 489.1 millimetres, about 13 percent more than the normal figure of 432.2 millimetres. The accumulated rainfall this year up to August was 2248.9 millimetres, a surplus of 18 percent compared to the normal figure of 1905.5 millimetres for the same period.

September 2017

Hong Kong’s weather was unseasonably hot in September 2017. The monthly mean temperature was 29.0 degrees, 1.3 degrees above the normal figure of 27.7 degrees and one of the hottest September since record began in 1884. The month was also drier than usual with a total rainfall of 192.4 millimetres, about 59 percent of the normal figure of 327.6 millimetres. The accumulated rainfall this year up to September was 2441.3 millimetres, a surplus of 9 percent compared to the normal figure of 2233.1 millimetres for the same period.

October 2017

With cooler air from the north only reaching the south China coastal areas later in the month, there were fine and unseasonably hot days in the first half of October 2017. The Very Hot Weather Warning was issued on a couple of occasions, the first time such warnings were required in the month of October. Overall, the monthly mean temperature was 26.3 degrees, 0.8 degree above the normal figure of 25.5 degrees. The monthly total rainfall was 99.6 millimetres, near the October normal of 100.9 millimetres. The accumulated rainfall this year up to October was 2540.9 millimetres, about 9 percent higher than the normal figure of 2334.0 millimetres for the same period.