The Weather of April 2022
4 May 2022
With dry northeast monsoon affecting Hong Kong and less moisture supply to the south China coast for most of the time in the month, April 2022 was much drier than usual in Hong Kong. The total rainfall in the month was 3.5 millimetres, only about 2 percent of the normal figure of 153.0 millimetres and the lowest on record for April. The accumulated rainfall recorded in the first four months of the year was 268.8 millimetres, about 11 percent below the normal figure of 300.4 millimetres for the same period. Moreover, the monthly mean relative humidity was 73 percent, the lowest on record for April since 1961. The month was also much sunnier than usual, the total duration of bright sunshine in the month was 191.1 hours, about 69 percent above the normal of 113.2 hours and the fifth highest on record for April. April 2022 was warmer than usual with a mean temperature of 23.7 degrees, 0.7 degree above the normal of 23.0 degrees.
A cold front moved across the coast of Guangdong on the morning of 1 April. Under the influence of the associated northeast monsoon, the weather of Hong Kong was cloudy and rather cool with a few rain patches on the first two days of the month. The temperature at the Observatory dropped to a minimum of 13.7 degrees on 2 April, the lowest of the month. Affected by a dry northeast monsoon, the weather of Hong Kong was generally fine on 3 – 10 April. It was also very dry during the day on 3 – 4 and 8 April. The relative humidity recorded at the Observatory once dropped to 22 percent on 8 April, the lowest on record in April since the automatic weather station was established at the Observatory's Headquarters in 1984.
Under light wind conditions, local weather was generally fine and hot during the day on 11 – 12 April. Affected by an upper-air disturbance, the weather turned mainly cloudy with a few showers on the morning of 13 April. The visibility was also rather low in some areas and once fell below 1000 metres at Waglan Island. Under the influence of an anticyclone aloft and the subsequent fresh to strong dry northeast monsoon, sunny and dry weather returned on the next two days.
Under the influence of a strong northeast monsoon, the weather of Hong Kong turned mainly cloudy and rather windy on 16 - 17 April. Affected by the cloud bands over southern China and the subsequent upper-air disturbance, it was cloudy with a few showers in the next two days. With the moderation of the northeast monsoon and thinning out of the cloud band, local weather gradually became sunnier on 20 – 21 April.
Affected by a humid southerly airstream, local weather was mainly cloudy with morning mist on 22 April. The weather became hot with sunny periods during the day on 23 - 27 April. There were also coastal fog on the mornings of 23 – 25 and 27 April. The visibility at Waglan Island once fell to around 200 metres on 25 April. Dominated by an anticyclone aloft, apart from coastal fog on the morning of 29 April, the weather of Hong Kong was generally fine and hot during the day on 28 – 29 April. With plenty of sunshine, the temperature at the Observatory rose to a maximum of 32.0 degrees on the afternoon of 29 April, the highest of the month. Affected by a fresh to strong easterly airstream, the weather turned mainly cloudy with showers on the last day of the month. There was also coastal fog in that morning.
Two tropical cyclones occurred over the South China Sea and the western North Pacific in April 2022.
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 April are tabulated in Table 2.
With dry northeast monsoon affecting Hong Kong and less moisture supply to the south China coast for most of the time in the month, April 2022 was much drier than usual in Hong Kong. The total rainfall in the month was 3.5 millimetres, only about 2 percent of the normal figure of 153.0 millimetres and the lowest on record for April. The accumulated rainfall recorded in the first four months of the year was 268.8 millimetres, about 11 percent below the normal figure of 300.4 millimetres for the same period. Moreover, the monthly mean relative humidity was 73 percent, the lowest on record for April since 1961. The month was also much sunnier than usual, the total duration of bright sunshine in the month was 191.1 hours, about 69 percent above the normal of 113.2 hours and the fifth highest on record for April. April 2022 was warmer than usual with a mean temperature of 23.7 degrees, 0.7 degree above the normal of 23.0 degrees.
A cold front moved across the coast of Guangdong on the morning of 1 April. Under the influence of the associated northeast monsoon, the weather of Hong Kong was cloudy and rather cool with a few rain patches on the first two days of the month. The temperature at the Observatory dropped to a minimum of 13.7 degrees on 2 April, the lowest of the month. Affected by a dry northeast monsoon, the weather of Hong Kong was generally fine on 3 – 10 April. It was also very dry during the day on 3 – 4 and 8 April. The relative humidity recorded at the Observatory once dropped to 22 percent on 8 April, the lowest on record in April since the automatic weather station was established at the Observatory's Headquarters in 1984.
Under light wind conditions, local weather was generally fine and hot during the day on 11 – 12 April. Affected by an upper-air disturbance, the weather turned mainly cloudy with a few showers on the morning of 13 April. The visibility was also rather low in some areas and once fell below 1000 metres at Waglan Island. Under the influence of an anticyclone aloft and the subsequent fresh to strong dry northeast monsoon, sunny and dry weather returned on the next two days.
Under the influence of a strong northeast monsoon, the weather of Hong Kong turned mainly cloudy and rather windy on 16 - 17 April. Affected by the cloud bands over southern China and the subsequent upper-air disturbance, it was cloudy with a few showers in the next two days. With the moderation of the northeast monsoon and thinning out of the cloud band, local weather gradually became sunnier on 20 – 21 April.
Affected by a humid southerly airstream, local weather was mainly cloudy with morning mist on 22 April. The weather became hot with sunny periods during the day on 23 - 27 April. There were also coastal fog on the mornings of 23 – 25 and 27 April. The visibility at Waglan Island once fell to around 200 metres on 25 April. Dominated by an anticyclone aloft, apart from coastal fog on the morning of 29 April, the weather of Hong Kong was generally fine and hot during the day on 28 – 29 April. With plenty of sunshine, the temperature at the Observatory rose to a maximum of 32.0 degrees on the afternoon of 29 April, the highest of the month. Affected by a fresh to strong easterly airstream, the weather turned mainly cloudy with showers on the last day of the month. There was also coastal fog in that morning.
Two tropical cyclones occurred over the South China Sea and the western North Pacific in April 2022.
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 April are tabulated in Table 2.
Warnings and Signals issued in April 2022
| Beginning Time | Ending Time | ||
|---|---|---|---|
| Day/Month | HKT | Day/Month | HKT |
| 1 / 4 | 0445 | 2 / 4 | 1530 |
| 15 / 4 | 0700 | 17 / 4 | 0920 |
| Beginning Time | Ending Time | ||
|---|---|---|---|
| Day/Month | HKT | Day/Month | HKT |
| 23 / 4 | 0055 | 23 / 4 | 0230 |
| Colour | Beginning Time | Ending Time | ||
|---|---|---|---|---|
| Day/Month | HKT | Day/Month | HKT | |
| Red | 3 / 4 | 0600 | 3 / 4 | 2230 |
| Red | 4 / 4 | 0600 | 5 / 4 | 2000 |
| Red | 8 / 4 | 0600 | 8 / 4 | 2230 |
| Yellow | 9 / 4 | 0600 | 9 / 4 | 2115 |
| Yellow | 10 / 4 | 0600 | 10 / 4 | 2100 |
| Yellow | 15 / 4 | 0600 | 15 / 4 | 1945 |
| Yellow | 16 / 4 | 0600 | 16 / 4 | 1800 |
| Yellow | 17 / 4 | 0600 | 17 / 4 | 1800 |
| Yellow | 18 / 4 | 0600 | 18 / 4 | 1800 |
| Beginning Time | Ending Time | ||
|---|---|---|---|
| Day/Month | HKT | Day/Month | HKT |
| 29 / 4 | 0645 | 29 / 4 | 1800 |
| Meteorological Element | Figure of the Month | Departure from Normal* |
|---|---|---|
| Mean Daily Maximum Air Temperature | 27.1 degrees C | 1.5 degrees above normal |
| Mean Air Temperature | 23.7 degrees C | 0.7 degree above normal |
| Mean Daily Minimum Air Temperature | 21.5 degrees C | 0.4 degree above normal |
| Mean Dew Point Temperature | 18.4 degrees C | 1.3 degrees below normal |
| Mean Relative Humidity | 73 % | 10 % below normal |
| Mean Cloud Amount | 58 % | 19 % below normal |
| Total Rainfall | 3.5 mm | 149.5 mm below normal |
| Number of hours of Reduced VisibilityΔ | 9 hours | 63.7 hours below normal§ |
| Total Bright Sunshine Duration | 191.1 hours | 77.9 hours above normal |
| Mean Daily Global Solar Radiation | 17.98 Megajoule / square metre | 5.46 Megajoule above normal |
| Total Evaporation | 111.4 mm | 24.2 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. |
| * | Departure from 1991 - 2020 climatological normal, except for number of hours of reduced visibility |
| § | Departure from mean value between 1997 and 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 |
