The Year's Weather - 2008

    Globally, the year 2008 ranked as the 10th warmest year on record. In Hong Kong, the average temperature in 2008 was slightly lower than those for previous years in this century. This was attributable to the La Nina phenomenon at the beginning of the year. The longest cold spell in 40 years occurred from 24 January to 16 February when the minimum temperature stayed below 12 degrees for 24 consecutive days. The year saw other new records. Record-breaking rain fell in April and June 2008, while October 2008 was the warmest October since record began in 1884. The year 2008 was also wetter than usual. The annual rainfall of 3066.2 millimetres was about 29 percent above normal.

    In 2008, the typhoon season started in mid-April, the second earliest onset time since 1946. Altogether six tropical cyclones affected Hong Kong and necessitated the issuance of local Tropical Cyclone Warning Signals, which were about normal. Four of them necessitated the issuance of the No. 8 or higher signals, making 2008 the year with the most No. 8 Signals since 1999. Typhoon Nuri crossed Hong Kong in August 2008 and necessitated the issuance of the Increasing Gale or Storm Signal No. 9. This was the first No. 9 signal since the passage of Typhoon Dujuan in September 2003.

    January was cloudier and wetter than usual. Cold weather started to affect Hong Kong on 24 January and lasted until 16 February. This exceptionally long cold spell was a result of the cold air from Siberia moving south incessantly to reach central and southern China, while moist air was transported from the South China Sea and from even as far as the Indian Ocean. The convergence between cold and moist air brought continuous cloudy, rainy and cold weather to Hong Kong. The monthly mean temperature of February was 13.3 degrees, the lowest for February in the past 40 years.

    March was warmer and sunnier than usual.

    April was warmer than usual. The passage of Typhoon Neoguri brought heavy rain to Hong Kong on 19 April, with a rainfall of 237.4 millimetres for the day breaking the April daily figure since record began. The heavy rain necessitated the issuance of the first Black Rainstorm Warning in 2008 which was also the earliest in the year since the start of the Rainstorm Warning System in 1992.

    May was cooler and drier than usual.

    The weather of June was marked by heavy rain and squally thunderstorms. The hourly rainfall of 145.5 millimetres recorded on 7 June between 8 and 9 a.m. was the highest since record began. The monthly total of 1346.1 millimetres was also a record high among all months since 1884.

    July was wetter than usual.

    August was sunnier and drier than usual. With long periods of sunshine, the monthly total global solar radiation in August was 564.48 megajoules per square metre, the second highest for August since record began.

    September was hotter and drier than usual. The monthly mean temperature of 29.0 degrees equaled the record set in 1969. The passage of Typhoon Hagupit in late September brought storm surges, which combined with high tides led to the highest sea level since Typhoon Wanda in 1962 and brought extensive flooding to many low-lying areas.

    October was unseasonably warm. Both the monthly mean temperature of 26.5 degrees and the mean daily minimum temperature of 24.9 degrees broke the records set in 1983 by 0.1 degrees and 0.2 degrees respectively.

    November was brighter and warmer than usual.

    December was warmer and drier than usual.

    Figure 1 shows the monthly rainfall in 2008 in comparison with the climatological normal values.

The minimum pressure recorded at the Hong Kong Observatory was 982.3 hectopascals at 1546 HKT on 22 August. The maximum air temperature recorded at the Hong Kong Observatory was 34.6 degrees Celsius at 1447 HKT on 28 July. The minimum air temperature recorded at the Hong Kong Observatory was 7.9 degrees Celsius at 0631 HKT on 3 February. The maximum gust peak speed recorded at Waglan Island was 157 kilometres per hour from 210 degrees at 1932 HKT on 22 August. The maximum instantaneous rate of rainfall recorded at King's Park exceeded [320] millimetres per hour at 0536 HKT on 7 June. # Reduced visibility refers to visibility below 8 kilometres when there is no fog, mist, or precipitation. - 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. & The calibration factors of the pyranometer at King's Park in 2006 and 2007 have been re-computed based on the results of a regional instrument comparison in Asia in 2007. The readings of total global solar radiation at King's Park in 2006 and 2007 displayed in this web page before 13 June 2008 have been revised on 13 June 2008 using the new calibration factors. * 1971-2000 Climatological Normal, unless otherwise specified § 1997-2007 Mean value [ ] upper limit of recorder ^ In case the data are not available from Waglan Island, observations of Cheung Chau or other nearby weather stations will be incorporated in computing the Prevailing Wind Direction and Mean Wind Speed