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.
Under the influence of the northeast monsoon, the weather in Hong Kong was mainly fine but appreciably cooler on the first two days of the month. With the setting in of an easterly airstream over the coast of Guangdong, the weather was a mixture of cloudy days, sunny periods and some light rain patches for the next five days. With the clouds thinning out gradually, there was more sunshine on 8 and 9 November, and the weather became warmer with temperatures at the Hong Kong Observatory rising to a maximum of 30.3 degrees, the highest of the month, on 9 November.
Meanwhile, a cold front over inland Guangdong moved southwards and crossed the coastal areas on the night of 9 November. A strong northeast monsoon associated with the cold front brought windy and slightly cooler weather with rain patches to the territory over the next four days. After a brighter day on 14 November, the setting in of a fresh to strong easterly airstream over the coast of Guangdong brought windy conditions again with more rain patches on 15 and 16 November.
The weather turned generally fine apart from some coastal mist patches on 17-18 November. Windy and mainly cloudy conditions returned with an easterly airstream for the ensuing three days, before clouds thinning out gradually and fine weather setting in on 22-24 November.
An intense northeast monsoon reached the coast of Guangdong on the morning of 25 November and winds strengthened gradually form the north that day. While the weather remained mostly fine under the dominance of a dry continental air mass, it became appreciably cooler as temperatures at the Hong Kong Observatory fell to a minimum of 15.3 degrees, the lowest of the month, on the morning of 27 November. With the moderation of the northeast monsoon, temperatures recovered gradually towards the end of the month.
One tropical cyclone occurred over the South China Sea and the western North Pacific in the month.
Details of issuance and cancellation of various warnings/signals
in the month are summarized in Tables 1.1 to 1.2. Monthly meteorological
figures and departures from normal for November are tabulated in Table 2.
|Beginning Time||Ending Time|
|10 / 11||0625||12 / 11||1345|
|25 / 11||1855||26 / 11||0745|
|Colour||Beginning Time||Ending Time|
|Yellow||1 / 11||0600||1 / 11||1945|
|Yellow||22 / 11||0600||22 / 11||1800|
|Red||26 / 11||0600||27 / 11||1800|
|Yellow||29 / 11||0600||29 / 11||1800|
|Meteorological Element||Figure of the Month||Departure from Normal*|
|Mean Daily Maximum Air Temperature||26.1 degrees C||2.0 degrees above normal|
|Mean Air Temperature||24.0 degrees C||2.2 degrees above normal|
|Mean Daily Minimum Air Temperature||22.4 degrees C||2.6 degrees above normal|
|Mean Dew Point Temperature||20.0 degrees C||4.0 degrees above normal|
|Mean Relative Humidity||79 %||8 % above normal|
|Mean Cloud Amount||66 %||12 % above normal|
|Total Rainfall||22.8 mm||14.8 mm below normal|
|Number of hours of Reduced VisibilityΔ||54 hours||86.3 hours below normal§|
|Total Bright Sunshine Duration||143.9 hours||36.2 hours below normal|
|Mean Daily Global Solar Radiation||11.69 Megajoule / square metre||0.59 Megajoule below normal|
|Total Evaporation||95.8 mm||3.7 mm below normal|
|Remarks :||All measurements were made at the Hong Kong Observatory except sunshine,
solar radiation and evaporation which were recorded at King's Park
Meteorological Station and visibility which was observed at the Hong
Kong International Airport.
The visibility readings at the Hong Kong International Airport are based on hourly observations by professional meteorological observers in 2004 and before, and average readings over the 10-minute period before the clock hour of the visibility meter near the middle of the south runway from 2005 onwards. The change of the data source in 2005 is an improvement of the visibility assessment using instrumented observations following the international trend.
* Departure from 1981 - 2010 climatological normal, except for number of hours of reduced visibility
§ Departure from mean value between 1997 and 2014
|Remarks :||Extremely high: above 95th percentile
Above normal: between 75th and 95th percentile
Normal: between 25th and 75th percentile
Below normal: between 5th and 25th percentile
Extremely low: below 5th percentile
Percentile and 5-day running average values are
computed based on the data from 1981 to 2010