The Weather of September 2022
5 October 2022
With much sunnier weather than usual in the month, September 2022 was exceptionally hot in Hong Kong. The monthly mean maximum temperature of 32.7 degrees, mean temperature of 29.6 degrees and mean minimum temperature of 27.3 degrees were 2.2 degrees, 1.7 degrees and 1.2 degrees above their corresponding normals and all of them were the second highest on record for September. There were 3 days with daily maximum temperatures at the Hong Kong Observatory equal to or higher than 35.0 degrees in the month, the highest number on record for September. The total duration of bright sunshine of 237.4 hours in the month was about 36 percent higher than the normal of 174.4 hours and the eighth highest on record for September. The month was also drier than usual with a monthly rainfall of only 171.2 millimetres, about 53 percent of the normal of 321.4 millimetres. The accumulated rainfall this year up to September was 1999.0 millimetres, about 11 percent lower than the normal figure of 2242.8 millimetres for the same period.
Under the influence of a weak northeast monsoon, it was very hot with sunny periods on the first day of the month in Hong Kong. High temperatures also triggered thundery showers over the territory in the afternoon. More than 70 millimetres of rainfall were recorded over Tai Po and North District of the New Territories. Affected by a dry continental airstream, the weather of Hong Kong was fine and dry on 2 – 6 September. It was also very hot during the day on 3 – 6 September.
Under the influence of an easterly airstream along the coast of Guangdong and a broad trough of low pressure over the South China Sea, local weather turned mainly cloudy with occasional showers and a few thunderstorms on 7 September. More than 20 millimetres of rainfall were recorded over many places in the New Territories and rainfall even exceeded 40 millimetres in Tai Po. Dominated by a ridge of high pressure, apart from isolated showers, it was generally fine and very hot during the day on 8 – 9 September. Under light wind conditions, apart from sunny intervals, high temperatures triggered a few showers the next day.
With the prevalence of a dry continental airstream, apart from a few showers, the weather of Hong Kong was generally fine and very hot on 11 – 17 September. It was also very dry during the day on 13 – 15 September and there were some haze on 12 – 13 and 16 – 17 September. With plenty of sunshine, the maximum temperature at the Observatory soared to 35.9 degrees on 13 September, the highest of the month and the highest maximum temperature for September on record. Moreover, the daily mean temperature at the Observatory reached 31.7 degrees on 13 and 14 September, both were the highest on record for September. The daily minimum temperature of 29.6 degrees on 14 September was also the highest on record for September.
Under light wind conditions, apart from sunny periods on 18 – 19 September, high temperatures triggered a few showers and squally thunderstorms over the territory on these two days. In particular, the isolated severe squally thunderstorms on the afternoon of 18 September brought intense gusts to Sai Kung, Lau Fau Shan and Tai O. With the onset of a fresh to strong northeast monsoon, there were sunny intervals and a few showers on 20 September. Apart from a few morning showers, the weather of Hong Kong turned generally fine on the next two days.
With the arrival of a replenishment of the northeast monsoon, local weather was mainly fine at first but became cloudy gradually with a few showers and thunderstorms later on 23 September. More than 20 millimetres of rainfall were recorded over the western part of the New Territories. Under the influence of the drier northeast monsoon, apart from a few showers, it was generally fine and dry on 24 – 26 September. Local weather turned cloudier and windier on 27 – 28 September. Affected by a broad trough of low pressure, it was mainly cloudy with showers and squally thunderstorms on 29 – 30 September. Showers were heavy at times on 30 September, with more than 100 millimetres of rainfall recorded over many places of the territory. Under the rain, the temperature at the Observatory dropped to a minimum of 24.8 degrees on that day, the lowest of the month.
Eight tropical cyclones occurred over the South China Sea and the western North Pacific in September 2022.
Details of issuance and cancellation of various warnings/signals in the month are summarized in Tables 1.1 to 1.6. Monthly meteorological figures and departures from normal for September are tabulated in Table 2.
With much sunnier weather than usual in the month, September 2022 was exceptionally hot in Hong Kong. The monthly mean maximum temperature of 32.7 degrees, mean temperature of 29.6 degrees and mean minimum temperature of 27.3 degrees were 2.2 degrees, 1.7 degrees and 1.2 degrees above their corresponding normals and all of them were the second highest on record for September. There were 3 days with daily maximum temperatures at the Hong Kong Observatory equal to or higher than 35.0 degrees in the month, the highest number on record for September. The total duration of bright sunshine of 237.4 hours in the month was about 36 percent higher than the normal of 174.4 hours and the eighth highest on record for September. The month was also drier than usual with a monthly rainfall of only 171.2 millimetres, about 53 percent of the normal of 321.4 millimetres. The accumulated rainfall this year up to September was 1999.0 millimetres, about 11 percent lower than the normal figure of 2242.8 millimetres for the same period.
Under the influence of a weak northeast monsoon, it was very hot with sunny periods on the first day of the month in Hong Kong. High temperatures also triggered thundery showers over the territory in the afternoon. More than 70 millimetres of rainfall were recorded over Tai Po and North District of the New Territories. Affected by a dry continental airstream, the weather of Hong Kong was fine and dry on 2 – 6 September. It was also very hot during the day on 3 – 6 September.
Under the influence of an easterly airstream along the coast of Guangdong and a broad trough of low pressure over the South China Sea, local weather turned mainly cloudy with occasional showers and a few thunderstorms on 7 September. More than 20 millimetres of rainfall were recorded over many places in the New Territories and rainfall even exceeded 40 millimetres in Tai Po. Dominated by a ridge of high pressure, apart from isolated showers, it was generally fine and very hot during the day on 8 – 9 September. Under light wind conditions, apart from sunny intervals, high temperatures triggered a few showers the next day.
With the prevalence of a dry continental airstream, apart from a few showers, the weather of Hong Kong was generally fine and very hot on 11 – 17 September. It was also very dry during the day on 13 – 15 September and there were some haze on 12 – 13 and 16 – 17 September. With plenty of sunshine, the maximum temperature at the Observatory soared to 35.9 degrees on 13 September, the highest of the month and the highest maximum temperature for September on record. Moreover, the daily mean temperature at the Observatory reached 31.7 degrees on 13 and 14 September, both were the highest on record for September. The daily minimum temperature of 29.6 degrees on 14 September was also the highest on record for September.
Under light wind conditions, apart from sunny periods on 18 – 19 September, high temperatures triggered a few showers and squally thunderstorms over the territory on these two days. In particular, the isolated severe squally thunderstorms on the afternoon of 18 September brought intense gusts to Sai Kung, Lau Fau Shan and Tai O. With the onset of a fresh to strong northeast monsoon, there were sunny intervals and a few showers on 20 September. Apart from a few morning showers, the weather of Hong Kong turned generally fine on the next two days.
With the arrival of a replenishment of the northeast monsoon, local weather was mainly fine at first but became cloudy gradually with a few showers and thunderstorms later on 23 September. More than 20 millimetres of rainfall were recorded over the western part of the New Territories. Under the influence of the drier northeast monsoon, apart from a few showers, it was generally fine and dry on 24 – 26 September. Local weather turned cloudier and windier on 27 – 28 September. Affected by a broad trough of low pressure, it was mainly cloudy with showers and squally thunderstorms on 29 – 30 September. Showers were heavy at times on 30 September, with more than 100 millimetres of rainfall recorded over many places of the territory. Under the rain, the temperature at the Observatory dropped to a minimum of 24.8 degrees on that day, the lowest of the month.
Eight tropical cyclones occurred over the South China Sea and the western North Pacific in September 2022.
Details of issuance and cancellation of various warnings/signals in the month are summarized in Tables 1.1 to 1.6. Monthly meteorological figures and departures from normal for September are tabulated in Table 2.
Warnings and Signals issued in September 2022
| Beginning Time | Ending Time | ||
|---|---|---|---|
| Day/Month | HKT | Day/Month | HKT |
| 27 / 9 | 0145 | 29 / 9 | 0245 |
| Colour | Beginning Time | Ending Time | ||
|---|---|---|---|---|
| Day/Month | HKT | Day/Month | HKT | |
| Amber | 30 / 9 | 1025 | 30 / 9 | 1415 |
| Amber | 30 / 9 | 2010 | 30 / 9 | 2110 |
| Beginning Time | Ending Time | ||
|---|---|---|---|
| Day/Month | HKT | Day/Month | HKT |
| 1 / 9 | 1400 | 1 / 9 | 1930 |
| 7 / 9 | 0235 | 7 / 9 | 1015 |
| 10 / 9 | 1523 | 10 / 9 | 1630 |
| 16 / 9 | 1434 | 16 / 9 | 1555 |
| 17 / 9 | 1550 | 17 / 9 | 1700 |
| 18 / 9 | 1445 | 18 / 9 | 2045 |
| 18 / 9 | 2123 | 19 / 9 | 0930 |
| 19 / 9 | 1430 | 19 / 9 | 1930 |
| 20 / 9 | 1015 | 20 / 9 | 1330 |
| 23 / 9 | 1540 | 23 / 9 | 1830 |
| 23 / 9 | 2145 | 23 / 9 | 2345 |
| 24 / 9 | 0040 | 24 / 9 | 0300 |
| 29 / 9 | 0630 | 29 / 9 | 1245 |
| 29 / 9 | 2305 | 30 / 9 | 0500 |
| 30 / 9 | 0820 | 30 / 9 | 2145 |
| Colour | Beginning Time | Ending Time | ||
|---|---|---|---|---|
| Day/Month | HKT | Day/Month | HKT | |
| Red | 2 / 9 | 1130 | 4 / 9 | 2330 |
| Red | 5 / 9 | 0600 | 6 / 9 | 1900 |
| Red | 9 / 9 | 0600 | 9 / 9 | 1945 |
| Yellow | 10 / 9 | 0600 | 10 / 9 | 1745 |
| Yellow | 11 / 9 | 0600 | 11 / 9 | 1800 |
| Yellow | 12 / 9 | 0600 | 12 / 9 | 2030 |
| Red | 13 / 9 | 0600 | 16 / 9 | 1900 |
| Yellow | 17 / 9 | 0600 | 17 / 9 | 1830 |
| Yellow | 18 / 9 | 0615 | 18 / 9 | 1645 |
| Yellow | 24 / 9 | 0845 | 24 / 9 | 1900 |
| Yellow | 25 / 9 | 0600 | 25 / 9 | 1945 |
| Beginning Time | Ending Time | ||
|---|---|---|---|
| Day/Month | HKT | Day/Month | HKT |
| 1 / 9 | 1110 | 1 / 9 | 1545 |
| 2 / 9 | 0645 | 2 / 9 | 1620 |
| 3 / 9 | 0645 | 3 / 9 | 1930 |
| 4 / 9 | 0645 | 6 / 9 | 1745 |
| 8 / 9 | 1130 | 9 / 9 | 1620 |
| 11 / 9 | 0645 | 11 / 9 | 1730 |
| 12 / 9 | 0645 | 19 / 9 | 1700 |
| 26 / 9 | 1235 | 26 / 9 | 1730 |
| Beginning Time | Ending Time | ||
|---|---|---|---|
| Day/Month | HKT | Day/Month | HKT |
| 1 / 9 | 1630 | 1 / 9 | 1920 |
| Meteorological Element | Figure of the Month | Departure from Normal* |
|---|---|---|
| Mean Daily Maximum Air Temperature | 32.7 degrees C | 2.2 degrees above normal |
| Mean Air Temperature | 29.6 degrees C | 1.7 degrees above normal |
| Mean Daily Minimum Air Temperature | 27.3 degrees C | 1.2 degrees above normal |
| Mean Dew Point Temperature | 22.8 degrees C | 0.8 degrees below normal |
| Mean Relative Humidity | 69 % | 9 % below normal |
| Mean Cloud Amount | 54 % | 12 % below normal |
| Total Rainfall | 171.2 mm | 150.2 mm below normal |
| Number of hours of Reduced VisibilityΔ | 5 hours | 63.0 hours below normal§ |
| Total Bright Sunshine Duration | 237.4 hours | 63.0 hours above normal |
| Mean Daily Global Solar Radiation | 18.33 Megajoule / square metre | 3.34 Megajoule above normal |
| Total Evaporation | 135.6 mm | 12.8 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 |
