The Weather of January 2023
With the northeast monsoon over Guangdong generally weaker than normal for most of the time in the month, despite a few cold interludes, January 2023 was overall warmer than usual in Hong Kong. The monthly mean temperature was 17.0 degrees, 0.5 degrees above the normal of 16.5 degrees. The month was also drier than usual. The monthly total rainfall was 18.2 millimetres, about 45 percent below the normal figure of 33.2 millimetres.
Under the influence of the northeast monsoon, the weather of Hong Kong was dry with sunny intervals on the first two days of the month. Affected by a replenishment of the northeast monsoon and a band of clouds over the coast of Guangdong, the weather turned mainly cloudy and cooler with a few rain patches on 3 January. With the thinning out of cloud band covering the coastal areas, there were sunny periods on the afternoon of 4 January. The weather became fine and mild during the day on 5 - 6 January under the moderation of the northeast monsoon.
With the setting in of a fresh to strong easterly airstream and the influence of a broad band of clouds associated with an upper-air disturbance, the weather of Hong Kong turned cloudier on 7 January. Local weather remained cloudy with a few rain patches on 8 – 12 January. Affected by a maritime airstream, the weather became mild and foggy with a few rain patches on 13 – 14 January. The visibility at Waglan Island once fell to around 100 metres on the morning of 13 January. With sunny periods during the day, the temperatures at the Observatory rose to a maximum of 24.7 degrees on 14 January, the highest of the month.
A cold front moved across the coast of Guangdong on the morning of 15 January. Locally, it was mainly cloudy with temperature falling significantly on 15 January. There were also a few rain and fog patches at first on that day. Under the influence of the northeast monsoon, it was cloudy and cold on 16 - 17 January. While it remained cold on the morning of 18 January, the weather turned generally fine and dry on 18 – 19 January under the influence of a continental airstream. Affected by an easterly airstream and a band of clouds covering the coast of Guangdong, the weather of Hong Kong was a mixture of sunny periods and a few rain patches on 20 – 22 January. Under light wind conditions, there were sunny periods with rather low visibility in some areas on 23 January.
Another cold front moved across the coast of Guangdong on the morning of 24 January. With winds strengthening from the north, apart from a few rain patches at first, the weather of Hong Kong became fine, dry and significantly colder on that day. Under the influence of the associated intense northeast monsoon, it was mainly cloudy with cold mornings on 25 – 26 January. With the arrival of a replenishment of the dry northeast monsoon, the weather turned generally fine and dry on 27 January. Local weather remained fine with cold mornings in the next three days. The temperatures at the Observatory fell to a minimum of 9.8 degrees on the morning of 29 January, the lowest of the month. It was also very dry during the day on 28 – 29 January. Moreover, there were frost reports in Tai Po and parts of the northeastern New Territories respectively on the mornings of 29 and 30 January. With the northeast monsoon moderating, there were sunny periods with rising temperature on the last day of the month.
There was no tropical cyclone over the South China Sea and the western North Pacific in January 2023.
Fog near Ma On Shan on 14 January 2023 (Courtesy of Otto CHENG)
Sea fog near Siu Sai Wan on 14 January 2023 (Courtesy of Janice MOK)
Sea fog at Victoria Harbour on 14 January 2023 (Courtesy of Kitty LEE)
Frost at Lin Ma Hang on 30 January 2023 (Courtesy of Mr. YIP Choi Hung)
Warnings and Signals issued in January 2023
|Beginning Time||Ending Time|
|15 / 1||1830||16 / 1||0945|
|24 / 1||0300||25 / 1||0945|
|27 / 1||0745||28 / 1||1145|
|Colour||Beginning Time||Ending Time|
|Yellow||1 / 1||0600||1 / 1||2230|
|Yellow||2 / 1||0645||2 / 1||2330|
|Red||6 / 1||0600||7 / 1||0600|
|Yellow||7 / 1||0600||7 / 1||2230|
|Yellow||15 / 1||1030||16 / 1||0600|
|Red||16 / 1||0600||16 / 1||2315|
|Red||17 / 1||0600||17 / 1||1145|
|Red||18 / 1||0600||19 / 1||2330|
|Yellow||23 / 1||0800||23 / 1||1800|
|Red||24 / 1||0600||25 / 1||0600|
|Yellow||25 / 1||0600||25 / 1||2330|
|Red||27 / 1||0600||30 / 1||2245|
|Red||31 / 1||1200||31 / 1||2330|
|Beginning Time||Ending Time|
|28 / 1||1630||29 / 1||0745|
|29 / 1||1630||30 / 1||0845|
|Beginning Time||Ending Time|
|15 / 1||1620||18 / 1||1115|
|24 / 1||1200||26 / 1||1130|
|27 / 1||1200||30 / 1||0945|
|Meteorological Element||Figure of the Month||Departure from Normal*|
|Mean Daily Maximum Air Temperature||19.4 degrees C||0.7 degree above normal|
|Mean Air Temperature||17.0 degrees C||0.5 degree above normal|
|Mean Daily Minimum Air Temperature||14.9 degrees C||0.3 degree above normal|
|Mean Dew Point Temperature||10.4 degrees C||1.3 degrees below normal|
|Mean Relative Humidity||67 %||7 % below normal|
|Mean Cloud Amount||68 %||6 % above normal|
|Total Rainfall||18.2 mm||15.0 mm below normal|
|Number of hours of Reduced VisibilityΔ||24 hours||180.1 hours below normal§|
|Total Bright Sunshine Duration||134.1 hours||11.7 hours below normal|
|Mean Daily Global Solar Radiation||11.44 Megajoule / square metre||0.89 Megajoule above normal|
|Total Evaporation||78.4 mm||9.3 mm above 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 1991 - 2020 climatological normal, except for number of hours of reduced visibility|
|§||Departure from mean value between 1997 and 2022|
|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