二零零八年天氣概況
全球天氣而言，二零零八年是有記錄以來第十溫暖的年份。本港二零零八年的年平均氣溫較過去數年稍低，主要是受到年初的「拉尼娜」現象影響。一月二十四日至二月十六日出現四十年來最長的寒潮，連續二十四天最低氣溫維持在12度以下。本年的其他新紀錄還有四月和六月的破紀錄雨量及一八八四年以來最溫暖的十月。二零零八年亦是較正常多雨的一年，年雨量達3066.2毫米，較正常多約百分之29。
颱風季節於二零零八年四月中旬開始，是自一九四六年以來第二早的風季開始時間。本年共有六個熱帶氣旋影響香港並需要發出本地熱帶氣旋警告信號，數目接近正常。當中四個需要發出八號或以上的信號，使本年成為自一九九九年以來最多八號信號的年份。颱風鸚鵡於二零零八年八月橫過香港，並需要發出九號烈風或暴風增強信號，是自二零零三年九月颱風杜鵑以來的首個九號信號。
二零零八年一月較正常多雲及多雨。寒冷天氣於一月二十四日至二月十六日影響本港。這次特長寒潮的成因主要是冷空氣不斷從西伯利亞南下影響華中及華南地區。此外，源於南海以至印度洋的潮濕氣流往北擴展，與冷空氣匯聚，引致本港出現持續多雲有雨及寒冷的天氣。二月的平均氣溫為13.3度，是四十年來二月份的最低記錄。
三月較正常溫暖及陽光充沛。
四月較正常溫暖。颱風浣熊於四月十九日為本港帶來大雨，當日錄得237.4毫米雨量，破了自有記錄以來四月份的單日最高雨量紀錄。該場大雨需要發出本年首個黑色暴雨警告，亦是自暴雨警告系統於一九九二年開始運作以來最早發出的黑色暴雨警告。
五月較正常清涼及少雨。
六月的天氣特色是有大雨及狂風雷暴。六月七日上午八時至九時錄得的每小時雨量為145.5毫米，是自有記錄以來最高的每小時雨量。月總雨量為1346.1毫米，亦創出自一八八四年以來最高的月雨量紀錄。
七月較正常多雨。
八月較正常少雨及陽光充沛。在陽光普照下，本月的太陽總輻射為每平方米564.48兆焦耳，是自有記錄以來八月份的第二高。
九月較正常炎熱及少雨。月平均氣溫是29.0度，平了1969年所創的最高紀錄。受到本月後期颱風黑格比帶來的風暴潮及漲潮的共同影響，海平面上升至自1962年颱風溫黛以來的最高水位紀錄，並為低窪地區帶來廣泛水浸。
十月天氣異常溫暖。本月平均氣溫為26.5度，而平均每日最低氣溫為24.9度，兩者皆破了一九八三年的紀錄，分別比舊紀錄高出了0.1度及0.2度。
十一月陽光較正常多及天氣溫暖。
十二月較正常溫暖及少雨。
圖1顯示二零零八年的月雨量與氣候正常數值的比較。
天文台於八月二十二日 15 時 46 分錄得本年最低氣壓 982.3 百帕斯卡。
天文台於七月二十八日 14 時 47 分錄得本年最高氣溫 34.6 攝氏度。
天文台於二月三日 6 時 31 分錄得本年最低氣溫 7.9 攝氏度。
橫瀾島於八月二十二日 19 時 32 分錄得本年最高陣風 157 公里/小時，風向 210 度。
京士柏於六月七日 5 時 36 分錄得本年最高瞬時降雨率超過 [320] 毫米/小時。
# 低能見度是指能見度低於 8 公里，不包括出現霧、薄霧或降水。
- 在2004年及以前，香港國際機場的能見度讀數是基於專業氣象觀測員每小時的觀測數據。在2005年及以後，讀數是採用位於機場南跑道中間的能見度儀表在每小時前10分鐘的平均數據。這與使用儀器觀測來改進能見度評估的國際趨勢是一致的。
- 在2007年10月10日前曾出現於此網頁內香港國際機場2005年及以後的低能見度時數資料乃基於專業氣象觀測員每小時的觀測數據。有關資料已於2007年10月10日起改為以機場南跑道中間之能見度儀表在每小時前10分鐘的平均數據計算。
⊕ 京士柏總日射表的2006年及2007年刻度因子已基於2007年的亞洲區區域儀器比對所得結果重新計算。在2008年6月13日前出現於此網頁內的京士柏2006年及2007年的太陽總輻射量數據已於2008年6月13日利用新的刻度因子作出修訂。
* 1971-2000 氣候平均值 (除特別列明外)
§ 1997-2007 平均值
[ ] 測量器的上限
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.
 Month |  Mean Pressure (hPa) | Air Temperature |  Mean Dew Point (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 | 1019.1 | 18.3 | 15.9 | 14.0 | 11.1 | 75 | 68 | 33.3 |
| February | 1020.7 | 16.0 | 13.3 | 11.3 | 8.1 | 72 | 72 | 27.5 |
| March | 1015.9 | 23.4 | 20.0 | 17.8 | 15.3 | 76 | 59 | 57.2 |
| April | 1012.4 | 25.5 | 23.1 | 21.5 | 20.3 | 85 | 84 | 255.0 |
| May | 1008.3 | 28.1 | 25.3 | 23.3 | 22.1 | 83 | 75 | 191.9 |
| June | 1006.2 | 28.9 | 26.7 | 24.8 | 24.4 | 88 | 81 | 1346.1 |
| July | 1005.7 | 31.0 | 28.4 | 26.5 | 24.9 | 82 | 70 | 471.1 |
| August | 1005.9 | 31.3 | 28.4 | 26.5 | 24.3 | 79 | 66 | 317.0 |
| September | 1007.8 | 32.0 | 29.0 | 26.8 | 23.8 | 75 | 66 | 159.2 |
| October | 1014.1 | 29.1 | 26.5 | 24.9 | 22.1 | 77 | 69 | 144.6 |
| November | 1018.0 | 24.5 | 21.9 | 19.8 | 14.7 | 65 | 48 | 54.3 |
| December | 1019.8 | 21.0 | 18.4 | 16.2 | 11.1 | 63 | 50 | 9.0 |
| mean or total | 1012.8 | 25.8 | 23.1 | 21.1 | 18.5 | 77 | 67 | 3066.2 |
| Normal* | 1013.0 | 25.6 | 23.1 | 21.1 | 18.8 | 78 | 67 | 2382.7 |
| Station | Hong Kong Observatory | |||||||
Month |  Number of hours of Reduced Visibility# (hours) |  Total Bright Sunshine (hours) | Mean Daily Global Solar Radiation⊕ (MJ/m2) | Total Evaporation (mm) | Prevailing Wind Direction (degrees) | Mean Wind Speed (km/h) |
| January | 226 | 124.8 | 9.47 | 66.4 | 350 | 22.8 |
| February | 316 | 96.8 | 10.16 | 63.2 | 350 | 25.5 |
| March | 265 | 176.8 | 14.40 | 92.4 | 070 | 19.5 |
| April | 172 | 86.6 | 11.17 | 76.7 | 060 | 21.1 |
| May | 97 | 124.8 | 14.05 | 103.4 | 080 | 20.2 |
| June | 13 | 75.5 | 10.60 | 103.7 | 200 | 21.7 |
| July | 29 | 179.0 | 16.91 | 132.3 | 240 | 18.0 |
| August | 6 | 215.5 | 18.21 | 140.7 | 240 | 19.9 |
| September | 186 | 213.9 | 16.75 | 146.1 | 090 | 18.2 |
| October | 230 | 180.6 | 14.53 | 115.7 | 080 | 28.5 |
| November | 128 | 216.0 | 14.23 | 113.9 | 080 | 27.4 |
| December | 283 | 188.5 | 12.22 | 89.5 | 360 | 24.3 |
| mean or total | 1951 | 1878.8 | 13.56 | 1244.0 | 070 | 22.3 |
| Normal* | 1407§ | 1842.9 | 13.23 | 1343.4 | 070 | 23.9 |
| Station | Hong Kong International Aiport | King's Park | Waglan Island | |||
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 |
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