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The Weather of February 2021

2 March 2021

With the northeast monsoon over southern China generally weaker than normal for most of the time in the month, February 2021 was much warmer and sunnier than usual in Hong Kong. The monthly mean maximum temperature of 23.5 degrees, monthly mean temperature of 19.8 degrees and monthly mean minimum temperature of 17.5 degrees were 4.1 degrees, 2.7 degrees and 2.2 degrees above their corresponding normals (or 4.6 degrees, 3.0 degrees and 2.5 degrees above their corresponding 1981-2010 normals) and respectively the second, third and fourth highest on record for February. The total duration of bright sunshine in the month was 205.1 hours, more than twice of the normal of 101.7 hours (or 110.9 hours above the 1981-2010 normal of 94.2 hours) and the fourth highest on record for February. Mainly attributing to the exceptional warm and sunny weather in February 2021, the winter from December 2020 to February 2021 was warmer than usual in Hong Kong. The mean temperature of 18.0 degrees was one of the seventh highest on record for the same period. The monthly rainfall was 62.1 millimetres, about 60 percent above the normal of 38.9 millimetres (or 14 percent above the 1981-2010 normal of 54.4 millimetres) in February. The accumulated rainfall recorded in the first two months of the year was 62.1 millimetres, a deficit of 14 percent compared to the normal of 71.9 millimetres (or 21 percent below the 1981-2010 normal of 78.9 millimetres) for the same period.

The weather of Hong Kong was fine and warm during the day on the first two days of the month. With plenty of sunshine, the temperature at the Observatory rose to a maximum of 27.6 degrees on the afternoon of 2 February, the highest of the month. A surge of the northeast monsoon arrived in the evening, local weather became windier and slightly cooler and remained so on the next day. Affected by a dry northeast monsoon, it was generally fine, warm and dry during the day on 4 – 7 February.

Under the influence of a strong easterly airstream, the weather of Hong Kong turned cloudier on 8 – 9 February. Affected by an upper-air disturbance and the associated rainband, local weather became cloudy with rain and cooler on 10 February. More than 30 millimetres of rainfall were generally recorded over the territory on that day. The weather remained cloudy and cool on 11 February with the temperature at the Observatory falling to a minimum of 15.3 degrees on the morning, the lowest of the month.

Under the influence of a dry northeast monsoon, the weather of Hong Kong turned fine with cool morning on 12 February, the first day of the Lunar New Year. Generally fine weather with warm daytimes persisted over the territory on 13-23 February.

With a fresh easterly airstream affecting the coast of Guangdong and a cloud band covering the northern part of the South China Sea, the weather of Hong Kong turned mainly cloudy on 24 February. There was a few rain patches on 25 February. It was warm with sunny intervals during the day on 26 February. A cold front moved across the coast of Guangdong that night and brought rainy weather to the territory. Under the influence of the northeast monsoon, local weather became cooler the next day with some rain in the morning. It remained mainly cloudy on the last day of the month.

One tropical cyclone occurred over the South China Sea and the western North Pacific in February 2021.

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 February are tabulated in Table 2.
 

Warnings and Signals issued in February 2021

Table 1.1   Strong Monsoon Signal
Beginning Time Ending Time
Day/Month HKT Day/Month HKT
2 / 2 2315 3 / 2 0945
8 / 2 1645 10 / 2 1145


Table 1.2   Fire Danger Warnings
Colour Beginning Time Ending Time
Day/Month HKT Day/Month HKT
Yellow 3 / 2 0600 3 / 2 2000
Yellow 4 / 2 0600 4 / 2 2000
Yellow 5 / 2 0600 5 / 2 2045
Yellow 6 / 2 0630 6 / 2 2000
Yellow 7 / 2 0645 7 / 2 2000
Yellow 12 / 2 0600 12 / 2 1945
Yellow 13 / 2 0600 13 / 2 1900
Yellow 14 / 2 0600 14 / 2 1900
Yellow 15 / 2 0600 15 / 2 2000
Yellow 17 / 2 0600 17 / 2 1945
Yellow 18 / 2 0600 18 / 2 2100
Yellow 19 / 2 0600 19 / 2 2230
Yellow 20 / 2 0600 20 / 2 1900
Yellow 21 / 2 0600 21 / 2 1930


Table 2   Figures and Departures from Normal - February 2021
Meteorological Element Figure of the Month Departure from Normal(1991-2020) Departure from Normal (1981-2010)
Mean Daily Maximum Air Temperature 23.5 degrees C 4.1 degrees above normal 4.6 degrees above normal
Mean Air Temperature 19.8 degrees C 2.7 degrees above normal 3.0 degrees above normal
Mean Daily Minimum Air Temperature 17.5 degrees C 2.2 degrees above normal 2.5 degrees above normal
Mean Dew Point Temperature 15.1 degrees C 1.9 degrees above normal 2.1 degrees above normal
Mean Relative Humidity 75 % 4 % below normal 5 % below normal
Mean Cloud Amount 41 % 31 % below normal 33 % below normal
Total Rainfall 62.1 mm 23.2 mm above normal 7.7 mm above normal
Number of hours of Reduced VisibilityΔ 6 hours 112.4 hours below normal§ 112.4 hours below normal§
Total Bright Sunshine Duration 205.1 hours 103.4 hours above normal 110.9 hours above normal
Mean Daily Global Solar Radiation 15.80 Megajoule / square metre 5.56 Megajoule above normal 6.41 Megajoule above normal
Total Evaporation 84.2 mm 23.8 mm above normal 24.3 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.

  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 mean value between 1997 and 2020
daily values of selected meteorological elements for HK for February 2021

The percentile map of mean temperature of February 2021

  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


Extract of Meteorological Observations in Hong Kong for February 2021