Skip Content

The Weather of December 2023

3 January 2024

With the northeast monsoon over the south China coast much weaker than normal, the weather of Hong Kong was exceptionally warm in the first half of December 2023.  While Hong Kong was affected by an intense winter monsoon in the second half of the month, December 2023 was still overall warmer than usual in Hong Kong.  The monthly mean temperature of 19.1 degrees was 0.9 degrees above the normal figure of 18.2 degrees and one of the ninth highest on record for December.  The month was also much drier than usual with a total rainfall of 0.9 millimetres, only about 3 percent of the normal figure of 28.8 millimetres.  The annual total rainfall of 2 774.5 millimetres was about 14 percent above the annual normal of 2 431.2 millimetres.

Affected by the northeast monsoon, apart from a few light rain patches, the weather of Hong Kong was mainly cloudy and dry with sunny intervals during the day on the first four days of the month.  Under light wind conditions and with the clouds thinning out, local weather became generally fine on 5 December.   While there were a few light rain patches and the visibility was relatively low in some areas on the morning of 6 December, the weather turned fine and dry in the afternoon with the setting in of a dry northeast monsoon and remained so the next two days.  It was also very dry during the day on 7 December.  Under the influence of a relatively humid easterly airstream, the weather turned cloudier on 9 December.   

Apart from cloudier weather and a few rain patches on the morning of 11 December, it was generally fine and rather warm on 10 – 12 December.  With abundant sunshine, the temperature at the Observatory rose to a maximum of 28.7 degrees on the afternoon of 12 December, the highest of the month and one of the highest maximum temperature on record for December.  

Under the influence of an easterly airstream and with a band of clouds covering the coast of Guangdong, the weather of Hong Kong turned mainly cloudy with a few rain patches on 13 – 14 December.  With the moderation of the easterly airstream, it was warm with sunny periods during the day the next day.  Meanwhile, a cold front formed over central China and moved across the coast of Guangdong on the morning of 16 December.  Locally, winds strengthened from the north with a few rain patches in the morning.  Temperatures fell appreciably with sunny intervals during the day.  Affected by the associated winter monsoon and with a band of clouds covering southern China, the weather of Hong Kong turned cloudy and cold on 17 December.  It was mainly cloudy with cool mornings on 18 – 19 December.

Affected by an intense replenishment of the winter monsoon, it was mainly cloudy and cold in Hong Kong on 20 – 23 December.  With a rainband moving across the coastal areas of Guangdong, there were a few rain patches in Hong Kong on the morning of 23 December.  The temperature at the Observatory dropped to a minimum of 8.1 degrees on that morning, the lowest of the month.  With the clouds thinning out, the weather of Hong Kong became fine and dry on 24 – 26 December.  It was also cold on the morning of 24 – 25 December.  Moreover, there were frost reports in Tai Po and Ta Kwu Ling on the morning of 24 December.  As the winter monsoon moderated, apart from a few light rain patches, local weather turned milder gradually with sunny periods during the day on 27 – 29 December.  Under light wind conditions, the weather was dry and rather warm with sunny periods during the day on the last two days of the month.  The visibility was also rather low in some areas.  The visibility at Chek Lap Kok once fell below 2 000 metres on the morning of 31 December.  The temperatures at the Observatory rose to a maximum of 25.7 degrees on the afternoon of 31 December, making it the warmest New Year's Eve on record.
Frost at Tai Po on 24 December 2023 (Courtesy of Irwin Wong)


One tropical cyclone occurred over the South China Sea and the western North Pacific in December 2023.

Details of issuance and cancellation of various warnings/signals in the month are summarized in Tables 1.1 to 1.4.  Monthly meteorological figures and departures from normal for December are tabulated in Table 2.

 

Warnings and Signals issued in December 2023

Table 1.1   Strong Monsoon Signal
Beginning Time Ending Time
Day/Month HKT Day/Month HKT
16 / 12 0600 17 / 12 0745
20 / 12 0625 20 / 12 1445
21 / 12 0550 22 / 12 1010


Table 1.2   Fire Danger Warnings
Colour Beginning Time Ending Time
Day/Month HKT Day/Month HKT
Yellow 2 / 12 0600 2 / 12 1850
Yellow 3 / 12 0600 3 / 12 1845
Red 7 / 12 0600 7 / 12 2300
Yellow 10 / 12 0600 10 / 12 1800
Yellow 16 / 12 1100 16 / 12 2330
Yellow 17 / 12 0600 17 / 12 2330
Red 20 / 12 0745 23 / 12 0915
Yellow 23 / 12 1230 24 / 12 0600
Red 24 / 12 0600 26 / 12 0600
Yellow 26 / 12 0600 26 / 12 1200
Red 26 / 12 1200 26 / 12 2145
Yellow 30 / 12 1015 30 / 12 1810
Yellow 31 / 12 1030 31 / 12 2245


Table 1.3   Frost Warning
Beginning Time Ending Time
Day/Month HKT Day/Month HKT
23 / 12 1630 24 / 12 0815
24 / 12 1630 25 / 12 0815


Table 1.4   Cold Weather Warning
Beginning Time Ending Time
Day/Month HKT Day/Month HKT
16 / 12 0600 18 / 12 0815
19 / 12 1620 25 / 12 1320


Table 2   Figures and Departures from Normal - December 2023
Meteorological Element Figure of the Month Departure from Normal*
Mean Daily Maximum Air Temperature 21.6 degrees C 1.2 degrees above normal
Mean Air Temperature 19.1 degrees C 0.9 degrees above normal
Mean Daily Minimum Air Temperature 17.1 degrees C 0.9 degrees above normal
Mean Dew Point Temperature 13.4 degrees C 1.0 degree above normal
Mean Relative Humidity 70 % normal
Mean Cloud Amount 71 % 14 % above normal
Total Rainfall 0.9 mm 27.9 mm below normal
Number of hours of Reduced VisibilityΔ 25 hours 156.9 hours below normal§
Total Bright Sunshine Duration 136.0 hours 25.6 hours below normal
Mean Daily Global Solar Radiation 10.70 Megajoule / square metre 0.21 Megajoule below normal
Total Evaporation 69.6 mm 11.3 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.
  Δ

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.
Before 10 October 2007, the number of hours of reduced visibility at the Hong Kong International Airport in 2005 and thereafter displayed in this web page was based on hourly visibility observations by professional meteorological observers. Since 10 October 2007, the data have been revised using the average visibility readings over the 10-minute period before the clock hour, as recorded by the visibility meter near the middle of the south runway.

  *   Departure from 1991 - 2020 climatological normal, except for number of hours of reduced visibility

  §   Departure from mean value between 1997 and 2022
Daily values of selected meteorological elements for Hong Kong for December 2023
The percentile map of mean temperature of December 2023

  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 1991 to 2020