The Year's Weather - 1997

    1997 was the wettest year since records began in 1884. Rainfall at the Hong Kong Observatory amounted to 3343.0 millimetres, 51 per cent above normal and exceeding the previous record set in 1982. Over 70% of the rain fell between June and August. This year's extreme rainfall coincided with an exceptionally strong El Nino event in the equatorial Pacific. The first tropical cyclone to affect Hong Kong did not come until the last day of July, which was the latest in any year on record. The passage of Typhoon Victor on 2 August necessitated the hoisting of the Increasing Gale or Storm Signal No. 9, which was the highest warning signal since Typhoon Ellen in 1983. The year's total duration of bright sunshine of 1558.2 hours was the shortest recorded. Also, the annual mean temperature was 23.4 degrees making 1997 the fourth warmest year on record.

    January was warmer and wetter than normal. The monthly mean temperature of 16.7 degrees and total rainfall of 44.6 millimetres were 0.9 degrees and 21.2 millimetres higher than the respective averages.

    The wet weather continued into February. The monthly rainfall totalled 111.7 millimetres which was 63.7 millimetres above normal.

    Sunnier and warmer weather was observed in March and the total sunshine duration amounted to 129.3 hours, 32.9 hours more than normal. As a result, the monthly mean temperature reached 20.1 degrees, the seventh highest for March.

    Cloudy conditions prevailed for most of April. The total bright sunshine duration was only 73.6 hours, the tenth lowest April record. The month was also characterized by misty weather.

    The weather in May was typical of the season in terms of precipitation. Heavy rain occurred on 8 May, necessitating the issuance of the first Rainstorm Red Warning and Landslip Warning in the year.

    Active troughs of low pressure brought a total rainfall of 783.6 millimetres in June making it the seventh wettest June on record. There were four days with rainfall exceeding 100 millimetres recorded at the Observatory.

    Exceptionally heavy rain associated with low pressure troughs continued in July. The month's total rainfall of 746.0 millimetres made it the fourth highest for the month of July and the accumulated rainfall since 1 January of 2154.7 millimetres was 64 per cent above normal. A Rainstorm Black Warning was issued on 1 July and Rainstorm Red Warnings were required on the first three days of the month. Landslip and Flood Warnings were also issued on two and eight occasions respectively. Furthermore, the month's total bright sunshine duration of 125.1 hours was the lowest on record. The first Tropical Cyclone Warning Signal of the year was hoisted on the last day of the month due to the approach of Typhoon Victor, which was the latest on record.

    The approach of Typhoon Victor in the late afternoon on 2 August necessitated the hoisting of the Increasing Gale or Storm Signal No.9, the highest tropical cyclone warning signal since Typhoon Ellen in 1983. Victor then weakened into a Severe Tropical Storm, but it still brought cyclonic storm force winds before it made landfall over the western part of Hong Kong that evening. During the passage of Victor, a man was drowned near Stanley as he tried to rescue two people swept away by high seas. About 60 people were injured in other storm related incidents. Torrential rain and thunderstorms caused three reported cases of landslips and 20 of flooding. In late August, Typhoon Zita brought more heavy rain to Hong Kong. A total of 829.0 millimetres of rainfall was recorded, making this August the fourth wettest on record.

    September was cooler than normal and the mean temperature of 26.4 degrees was the eighth lowest for the month. With no tropical cyclones in our vicinity, the monthly mean pressure reached 1012.1 hectopascals, the highest on record for September.

    The rainfall in October amounted to only 112.8 millimetres or 32.0 millimetres below average. However, the accumulated rainfall since 1 January of 3329.4 millimetres was 55 per cent above the normal figure, surpassing the previous record maximum annual rainfall of 3247.5 millimetres set in 1982.

    A weak northeast monsoon coupled with an unseasonal southerly airstream gave rise to the warmest November on record. The mean temperature of 23.1 degrees equalled to the previous record set in 1966. The mean minimum temperature of 21.2 degrees also ranked highest for November.

    December was also warmer than normal with a mean temperature of 18.9 degrees, the seventh highest for the month. However, the total bright sunshine duration of 100.4 hours was the fourth lowest for December.

Summary of Meteorological Observations in Hong Kong, 1997
 

Month	Mean Pressure (hPa)	Air     Temperature			Mean Dew Point Temperature (deg. C)	Mean Relative Humidity (%)	Mean Amount of Cloud (%)	Total Rainfall (mm)
		Mean Daily Maximum (deg. C)	Mean (deg. C)	Mean Daily Minimum (deg. C)
January	1019.3	18.9	16.7	14.7	11.1	71	47	44.6
February	1018.3	18.0	16.1	14.6	12.3	79	76	111.7
March	1016.9	22.5	20.1	18.3	16.7	82	68	34.8
April	1014.1	25.0	22.8	21.2	19.5	83	84	133.2
May	1008.6	28.5	26.1	24.1	22.6	82	75	300.8
June	1006.2	29.5	27.3	25.6	24.6	85	84	783.6
July	1006.6	30.3	28.1	26.1	25.0	84	78	746.0
August	1003.4	30.7	28.4	26.3	25.1	83	77	829.0
September	1012.1	28.5	26.4	24.5	22.4	79	74	232.9
October	1016.0	27.9	25.9	24.3	21.7	78	58	112.8
November	1017.9	25.3	23.1	21.2	17.2	71	53	7.1
December	1020.3	20.9	18.9	17.1	14.3	75	64	6.5
Mean/Total	1013.3	25.5	23.4	21.5	19.4	79	70	3343.0
Normal	1012.9	25.7	23.0	20.9	18.6	77	65	2214.3
Station	Hong  Kong  Observatory

Month	Total Bright Sunshine (hours)	Mean Daily Global Solar Radiation (MJ/m2)	Total Evaporation (mm)	Prevailing Wind Direction (degrees)	Mean Wind Speed (km/h)
January	173.6	11.28	70.9	060	27.3
February	85.5	9.75	54.8	060	30.7
March	129.3	11.60	75.3	060	23.1
April	73.6	11.59	81.7	070	21.3
May	136.7	13.21	111.1	080	20.1
June	99.7	11.72	96.9	220	20.2
July	125.1	12.31	106.0	190	21.0
August	141.3	13.23	130.3	240	27.1
September	117.1	12.25	107.0	010	23.1
October	173.3	13.24	105.9	090	20.1
November	202.6	12.85	100.5	090	23.5
December	100.4	8.64	68.9	050	26.6
Mean/Total	1558.2	11.82	1109.3	070	23.6
Normal	1948.1	14.46	1528.8	080	22.6
Station	King's  Park			Waglan  Island^