Appendix F Meteorological Data

November 2015

November 2015 emerged as the warmest November in Hong Kong since records began in 1884 with a record-breaking mean temperature of 24.0 degrees, 2.2 degrees above the November normal of 21.8 degrees. The anomalously warm weather was mainly attributed to the relatively high sea surface temperatures over the northern part of the South China Sea and the rather weak advection of cold air from the north despite the prevailing northeast monsoon. The month was also drier than usual with only 22.8 millimetres of rainfall, a deficit of about 39 percent as compared to the normal figure of 37.6 millimetres. The accumulated rainfall of 1810.2 millimetres since 1 January was about 24 percent below the normal figure of 2371.7 millimetres for the same period.

December 2015

With a relatively humid air mass affecting the territory for most part of the month, the weather of December 2015 was gloomier and wetter than usual. The total duration of sunshine recorded in the month was 75.9 hours, only about 44 percent of the normal figure of 172.2 hours. Two rainy episodes on 5 and 9 December mostly contributed to the monthly rainfall of 64.3 millimetres, more than double the normal figure of 26.8 millimetres. However, the annual rainfall of 1874.5 millimetres was still about 22 percent below the normal of 2398.5 millimetres. December 2015 was also warmer than usual with a monthly mean temperature of 18.6 degrees, 0.7 degrees above the normal figure of 17.9 degrees.

January 2016

January 2016 was characterized by an intense cold surge in the latter part of the month and exceptionally high monthly rainfall. The unseasonably warm weather in the first three weeks of the month was totally offset by the freezing temperatures during the 3-day period of 23 - 25 January. The mean sea level pressure of 1037.7 hectopascals on 24 January was the highest ever recorded at the Observatory. Yet the monthly averaged temperature of 16.0 degrees turned out to be deceptively unremarkable, only 0.3 degree below normal. With upper-air disturbances repeatedly affecting the south China coastal areas and bringing outbreaks of heavy rain, the Observatory recorded an all-time high monthly rainfall of 266.9 millimetres, more than ten times the January normal of 24.7 millimetres and easily breaking the previous record of 214.3 millimetres set way back in January 1887. The heavy rain on 5 January also broke the hourly rainfall record for January.

February 2016

 With frequent replenishments of the winter monsoon, February 2016 was cooler than usual. The monthly mean temperature was 15.5 degrees, 1.3 degrees below the normal figure of 16.8 degrees. The month was also drier than usual with 24.8 millimetres of rainfall, only about 46 percent of the normal figure of 54.4 millimetres. However, due to an extremely rainy January, the accumulated rainfall of 291.7 millimetres in the first two months of the year was more than three times the normal figure of 79.1 millimetres for the same period.

March 2016

With the northeast monsoon and a humid maritime airstream competing for dominance over the south China coast, March 2016 in Hong Kong was characterized by gloomy, rainy and humid weather with fluctuating temperatures. Overall, the month was cooler than usual with rainfall above normal. The monthly mean temperature was 17.5 degrees, 1.6 degrees lower than the normal figure of 19.1 degrees. The monthly total rainfall was 148.7 millimetres, about 81 percent more than the normal figure of 82.2 millimetres. The accumulated rainfall of 440.4 millimetres in the first three months of the year was about 1.7 times above the normal figure of 161.3 millimetres for the same period.

April 2016

With a maritime airstream trying to exert control over the coastal areas of Guangdong in a change of seasons, the weather of April 2016 was exceptionally humid and gloomy. The monthly mean relative humidity was 89 percent, six percent higher than normal and also the most humid for April since 1961. Under long spells of clouds, fog or mist, the sunshine duration of 6.9 hours on 6 April already made it the sunniest day in the month. The total duration of bright sunshine recorded in the month was only 55.4 hours, around 54 percent of normal and the sixth lowest for April on record. The month was also warmer and rainier than usual. The monthly mean temperature was 23.6 degrees, 1.0 degrees above the normal figure of 22.6 degrees. The monthly total rainfall was 211.4 millimetres, about 21 percent more than the normal figure of 174.7 millimetres. The accumulated rainfall of 651.8 millimetres in the first four months of the year was nearly double the normal figure of 336.1 millimetres for the same period.

May 2016

The weather for May 2016 was warmer and drier than usual. The monthly mean temperature was 26.7 degrees, 0.8 degree above the normal figure of 25.9 degrees. Despite several rainstorms in the month, the monthly total rainfall was only 233.6 millimetres, about 23 percent below the normal figure of 304.7 millimetres. However, the accumulated rainfall of 885.4 millimetres in the first five months of the year was still about 38 percent more than the normal figure of 640.8 millimetres for the same period.

June 2016

June 2016 was characterized by rainy weather during the first part of the month and persistent very hot weather in the latter part. Overall, the month was exceptionally hot. The monthly mean temperature was 29.4 degrees, 1.5 degrees higher than the normal figure of 27.9 degrees and the second hottest June on record. The monthly mean maximum temperature of 32.4 degrees and minimum temperature of 27.5 degrees were respectively the highest and the second highest for June. Despite there were several heavy rain episodes in the first half of the month, the monthly total rainfall was only 347.4 millimetres, about 24 percent below the normal figure of 456.1 millimetres. The accumulated rainfall for the first half year of 1232.8 millimetres was about 12 percent above the normal figure of 1096.9 millimetres for the same period.

July 2016

With long spells of sunny skies under the dominance of the subtropical ridge, the weather was unusually hot in July 2016. The monthly mean temperature of 29.8 degrees was 1.0 degree higher than the normal figure of 28.8 degrees, equalling the previous highest record set in 2014. The month was much drier than usual with only 175.9 millimetres of rainfall, less than half of the July normal of 376.5 millimetres. The accumulated rainfall of 1408.7 millimetres for the first seven months was about 4 percent below the normal figure of 1473.3 millimetres for the same period.

August 2016

The weather of August 2016 was generally rainy with less sunshine than usual. The total duration of sunshine recorded in the month was 148.5 hours, about 21 percent below the normal figure of 188.9 hours. The monthly total rainfall was 532.7 millimetres, about 23 percent above the normal figure of 432.2 millimetres. The accumulated rainfall of 1941.4 millimetres for the first eight months was about 2 percent above the normal figure of 1905.5 millimetres for the same period.

September 2016

With rainy weather dominating the first part of the month, September 2016 was gloomier than usual. The total duration of sunshine recorded in the month was 135.7 hours, 36.6 hours below the normal figure of 172.3 hours and the seventh lowest on record for September. However, the month was slightly warmer than usual with a monthly mean temperature of 27.9 degrees, 0.2 degree higher than the normal figure of 27.7 degrees. The monthly total rainfall was 323.1 millimetres, slightly below the normal figure of 327.6 millimetres. The accumulated rainfall of 2264.5 millimetres for the first nine months was about 1 percent above the normal figure of 2233.1 millimetres for the same period.

October 2016

October 2016 was marked by record-breaking high mean temperatures, despite a succession of cyclonic systems passing by in the vicinity of Hong Kong and the duration of sunshine falling under 80 percent of the October normal. The monthly mean maximum temperature of 29.1 degrees, monthly mean temperature of 26.8 degrees and monthly mean minimum temperature of 25.0 degrees were all 1.3 degrees above their respective normals and were the highest ever on record for October. After the passage of the remnant circulation of Severe Typhoon Megi over southern China in late September, Tropical Storm Aere hovered for days over the coastal waters of Guangdong at the doorstep of Hong Kong in early October. Then came Super Typhoon Sarika and Super Typhoon Haima in less than a week between 16 and 21 October. The former brought torrential rain that broke the October hourly rainfall record and triggered the Black Rainstorm Warning on 19 October, while the latter led to the issuance of the No. 8 Gale or Storm Signal on 21 October. The monthly rainfall recorded at the Hong Kong Observatory was 624.4 millimetres, more than six times the October normal of 100.9 millimetres and the second highest on record for October. The accumulated rainfall of 2888.9 millimetres up to the end of October was about 24 percent above the normal figure of 2334.0 millimetres for the same period.