(7月19日) 颱風莫拉菲在中國廣東省深圳市龍崗區南澳街道沿海地區登陸，其中心於香港天文台北面 40 公里掠過，天文台發出九號烈風或暴風信號，是 2008 年以來第二次。莫拉菲為自 2003 年颱風杜鵑以來正面吹襲香港的最強颱風。

(Jul 19) Typhoon Molave made landfall at Longgang District of Shenzhen City, and it was only 40 kilometres from the Observatory at its closest point of approach. The Observatory issued the #9 Increasing Gale or Storm Signal for the second time in as many years. Molave is the strongest typhoon to make a "direct hit" since Typhoon Dujuan in 2003.

(8月7日前後) 颱風莫拉克在台灣花蓮縣登陸，登陸時颱風中心附近最大風力13級。莫拉克於台灣減弱為強烈熱帶風暴，並於 9 日再度登陸福建省霞浦縣。莫拉克引進西南氣流，台灣經歷 50 年來最嚴重的雨災，阿里山於三天內雨量超過 2500 毫米；總計造成超過 600 人死亡，是為 "八八水災"。

(Around Aug 7) Typhoon Morakot made landfall at Hualien, producing winds of force 13. Morakot weakened into a severe tropical cyclone in Taiwan, and made landfall again at Fujian on August 9. The southwesterly airstream induced by Morakot triggered the heaviest rainfall in many areas in Taiwan since 1959, with Alishan recording 2500 mm of rainfall in just three days, and the death toll exceeded 600 as a result.

(9月14日) 颱風巨爵於本港 130 公里外掠過，天文台於下午 5 時 55 分發出八號烈風或暴風信號，共維持 16 小時 20 分鐘。當晚本港風勢強勁，適逢 15 日凌晨大潮，大澳等低窪地區出現水浸。巨爵於 15 日清晨在中國廣東省台山市北陡鎮沿海地區登陸，廣東省最大風速達 14 級。它造成至少 9 人死亡，9 人失蹤。

(Sep 14) Typhoon Koppu passed at about 130 kilometres from the Observatory; the #8 Gale or Storm Signal was issued at 5:55 p.m. and lasted for 16 hours 20 minutes. Winds were very strong that night in the territory; coupled with high tides the next morning, low-lying areas like Tai O were flooded. Koppu made landfall at Taishan, Guangdong on September 15, creating winds of up to force 14. The storm is responsible for at least 9 deaths and 9 others went missing.

(9月尾至10月中) 於 9 月尾形成的超強颱風芭瑪逐步減弱為熱帶風暴，並三度於菲律賓呂宋地區登陸。芭瑪於 10 月中橫過南海北部，於北部灣再度增強，最後於 14 日在越南北部登陸。芭瑪於菲律賓造成最少 438 人死亡，50 人失蹤；它於 9 月 27 日形成，在 10 月 14 日消散，前後共 17 日，聯合颱風警報中心對其作出 68 次發佈，為繼 1972 年颱風麗妲後西北太平洋發佈數量最多的氣旋。

(Late Sep to Mid-Oct) Super typhoon Parma formed in late September; it gradually weakened into a tropical storm and made landfall in Luzon for three times. Parma traversed the northern South China Sea in mid-October, and re-intensified in the Gulf of Tonkin. It finally made landfall in northern Vietnam on October 14. Parma killed at least 438 people in the Philippines with another 50 missing. Parma's lifetime reached 17 days from its genesis to dissipation, necessitating 68 bulletins from the JTWC. This is the second highest number of bulletins issued for a tropical cyclone in the northwestern Pacific, after Typhoon Rita in 1972.

(11月25日) 超強颱風妮妲於西北太平洋爆發增強，於 25 日晚至 26 日凌晨達到巔峰強度，風力達每小時 160 海里 (295 公里)，為本年全球最強的熱帶氣旋，亦為聯合颱風警報中心自 1997 年以來對西北太平洋熱帶氣旋所給出的最高強度。

(Nov 25) Super typhoon Nida deepened rapidly after its formation, reaching peak strength on November 25/26. The wind speed was estimated at 160 knots (295 km/h), and Nida became the strongest tropical cyclone in any basin this year. This is also the highest wind speed designated by the JTWC to a tropical cyclone in the northwestern Pacific Ocean since 1997.

(7月22日) 本世紀最長的日全食於今天上演，亞洲和太平洋部分地區出現日食，其中印度中部、尼泊爾東南部、不丹、孟加拉國北部、緬甸北部、中國中部長江流域、日本琉球 群島、中西太平洋等部分地區出現日全食。香港則可見自 1958 年以來食分最大的日食，為此不少市民到太空館和屯門一間小學觀看。

(Jul 22) The longest total solar eclipse of this century occurred today. The majority of Asia and parts of the Pacific Ocean witnessed the eclipse to varying degrees, while the path of totality passed through central India, southeastern Nepal, Bhutan, northern Bangladesh, northern Myanmar, central China, Ryukyu Islands and central/western Pacific Ocean. Hong Kong also experienced a partial eclipse of the highest magnitude since 1958, and many citizens gathered at the Space Museum and a primary school in Tuen Mun to witness the event.

(8月4至9日) 受一熱帶低氣壓的外圍下沉氣流影響，天文台錄得 34.9 度之全年最高溫。該低氣壓稍後增強為強烈熱帶風暴天鵝，並於 4 日晚在香港西南 110 公里掠過，天文台發出八號烈風或暴風信號，但風力欠奉。天鵝稍後在廣東省台山市海宴鎮附近沿海地區登陸。天鵝受另一氣旋莫拉克的影響，於海南地區打轉，最後於 9 日晚在香港以南約三百公里處減弱為低壓區。

(Aug 4-9) Affected by the subsidence associated with a tropical depression, the Observatory recorded an air temperature of 34.9 degrees, the highest in this year. This tropical depression later intensified into Severe tropical storm Goni, which necessitated the #8 Gale or Storm Signal on August 4, and was 110 km southwest of the Observatory at its closest point of approach. Winds were not very strong in the territory, however. Goni later made landfall at Taishan, Guangdong. Affected by tropical cyclone Morakot, Goni made a loop around Hainan and finally dissipated in waters some 300 km south of Hong Kong on August 9.

(3月18日) 為提高市民對較強颱風的警覺，天文台增加 "強颱風" 和 "超強颱風" 兩個熱帶氣旋分類等級。

(Mar 18) To raise awareness about intense tropical cyclones, the Observatory added two more categories, "Severe typhoon" and "Super typhoon", to its tropical cyclone classification system.

(1月10至11日) 受到一股強烈東北季候風影響，本港氣溫跌至 10 度以下。天文台曾兩度預計市區最低溫度將跌至 8 度，而最終天文台於 1 月 10 日錄得全年最低氣溫 9.4 度。打鼓嶺於翌日則錄得 -0.8 度的低溫，為 1985 年有紀錄以來最低氣溫。

(Jan 10-11) Affected by an intense surge of northeast monsoon, temperatures in the territory plummeted to below 10 degrees. The Observatory predicted twice a minimum of 8 degrees Celsius in urban areas, and the lowest recorded temperature was 9.4 degrees at the Observatory on January 10. This is the lowest temperature recorded this year. Ta Kwu Ling registered -0.8 degrees on January 11, the lowest since records began in 1985.

(11月18日) 中國各地於 11 月接連受冷空氣影響，冷雪天氣比正常早一個月來臨，而香港於 18 日錄得 9.7 度的低溫，是自 1987 年以來 11 月錄到的最低溫，更破旬內最低氣溫的紀錄。

(Nov 18) Almost everywhere in China was affected by a series of cold surges in November, with snow falling one month earlier than normal, and in Hong Kong a minimum temperature of 9.7 degrees was recorded on November 18, the coldest in November since 1987. This temperature is a record low for the second 10-day period of November (November 11 to November 20).

(2月) 本月東北季候風偏弱，為 1884 年有紀錄以來最暖的二月，平均溫度達 20.5 度，比平均高出 4.2 度。此外，本月 25 日錄得的 28.3 度是有紀錄以來二月份的最高氣溫。

(Feb) Due to the abnormally weak northeast monsoon, Hong Kong experienced the warmest February since records began in 1884. The average temperature was 20.5 degrees, 4.2 degrees higher than average. Moreover, the maximum temperature of 28.3 degrees recorded on February 25 is the warmest on record in February.

(9月26日) 熱帶風暴凱薩娜橫過呂宋島，馬尼拉出現 42 年來最嚴重的雨災。由於水浸情況嚴重，菲國多個省份於當天宣布進入災難狀態，最終死亡人數超過 400。凱薩娜其後進入南海，其風圈之大令天文台於 27 日晚發出一號戒備信號。凱薩娜進而增強為颱風，並在 29 日於越南登陸，造成超過 180 人死亡。

(Sep 26) Tropical storm Ketsana crossed Luzon and inflicted the worst flooding in Manila since 1967. A state of calamity was declared in the Philippines on that day, and it was responsible for more than 400 deaths in the country. Ketsana later entered the South China Sea; its wide wind radius prompted the Observatory to issue the Standby Signal on September 27. Ketsana then intensified into a typhoon and made landfall in central Vietnam on September 29, killing another 180.

(12月中下旬) 歐洲和北美洲分別受暴風雪影響，其中美國東北部普遍錄得超過 40 厘米降雪，並打破首都華盛頓的 24 小時降雪量紀錄。歐洲大部分地區溫度跌至 0 度以下，德國更錄得零下 33 攝氏度的低溫，而多架歐洲之星列車則因暴風雪影響於英法海底隧道發生故障，其後全面停駛 3 天。截至 12 月 22 日，歐洲的雪災造成超過 80 人死亡，其中波蘭最少有 42 人凍死，烏克蘭亦有 27 人。

(Mid to late Dec) Europe and North America were affected by severe snowstorms in late December. More than 40 centimetres of snow have fallen in most parts of northeastern US, and the 24-hour snowfall record in Washington D.C. was broken. In Europe, temperatures in most regions plummeted to below freezing point, and even fell to -33 degrees in Germany. As a result of the snowstorm, several Eurostar trains were stuck in the Channel Tunnel, and services were suspended for three days. As of December 22, more than 80 people have died from the cold spell, of which at least 42 were from Poland and another 27 from Ukraine.

(12月7至19日) 2009 年聯合國氣候變化大會在丹麥首都哥本哈根舉行，初時預料會制訂新的協議，以承繼將於 2012 年到期的京都議定書，但最終只能由美國、巴西、南非、印度和中國達成一份不具法律約束力的聲明。

(Dec 7-19) The United Nations Climate Change Conference 2009 was held in Copenhagen. It was anticipated that a framework for climate change mitigation beyond 2012 was to be set up, succeeding Kyoto Protocol which will expire in 2012. However, only a non legally binding document was agreed among the US, Brazil, South Africa, India and China on the final day of the conference.

(3月5日) 受到與一道冷鋒相關連的雨帶影響，天文台於今天下午兩度發出黃色暴雨警告，為暴雨警告信號制定以來最早的一次。

(Mar 5) Affected by the rainbands associated with a cold front, The Observatory issued the Amber Rainstorm Warning twice in the afternoon. This is the earliest issuance of such signal since its implementation.

(9月9日) 本港由八月底開始持續酷熱，天文台由 8 月 23 日至 9 月 8 日每天的最高溫度均高於 33 度；酷熱天氣警告於 9 月 2 日至 9 月 9 日連續生效 164 小時，是制定警告以來連續發出時間第二長。

(Sep 9) Hong Kong experienced a heat wave since late August, with the Observatory's maximum temperature exceeding 33 degrees every day from August 23 to September 8. The Very Hot Weather Warning was in force for a continuous 164 hours from September 2 to September 9, which is the second longest (continuous) duration since the implementation of the warning.

(9月29日) 太平洋薩摩亞群島附近海域發生震級為 8.0 的強烈地震，並引發海嘯，造成薩摩亞和美屬薩摩亞至少 189 人死亡。翌日，印尼蘇門答臘地區亦發生 7.6 級地震，超過 1100 人死亡。薩摩亞群島的地震為本年度至今最強的一次。

(Sep 29) An 8.0 magnitude earthquake stroke the Samoa Islands and triggered a tsunami; the final death toll reached 189. On the next day, Sumatra also experienced a magnitude 7.6 earthquake, killing more than 1100. The Samoa earthquake is the strongest this year up till now.

(11月13日) 美國太空總署宣布，月球坑觀測和傳感衛星在撞擊月球過程中獲得的數據顯示該地有水存在。

(Nov 13) NASA claimed to have discovered water after the LCROSS satellite crashed near the South Pole of the Moon in October.

(8月19日) 有市民於早上約 8 時發現蒲台島附近海域出現水龍捲。天文台解釋，雖然香港當天大致天晴，但局部地區有較強對流發展，因而形成驟雨及水龍捲。

(Aug 19) Several citizens spotted a waterspout briefly at about 8 a.m. near Po Toi Island. The Observatory later explained that although it was generally fine that day, there were localized strong convections which led to the formation of showers and this waterspout.

(3月28日) 全球 80 多個國家響應由世界自然基金會發起的環保活動 "地球一小時" 。本港 600 間機構、超過 1800 座大廈在晚上 8 時 30 分，響應全球熄燈一小時行動，表達對氣候變化的關注。

(Mar 28) More than 80 countries participated in the "Earth Hour" event organized by the World Wide Fund for Nature. 1800 buildings from 600 organizations in Hong Kong switched off unnecessary lighting from 8:30 to 9:30 p.m. on March 28 to express their awareness of global warming.

(12月下旬) 菲律賓馬榮火山出現劇烈活動，當地火山學及地震學研究所於 20 日將警告級別提升至 4 級，表示猛烈爆發可能於未來數天出現，約五萬人需要撤離。

(Late Dec) The Mayon Volcano in the Philippines was showing violent activities, and the Philippine Institute of Volcanology and Seismology raised the alert to level 4 on December 20, indicating a violent eruption is likely in the next few days. About 50,000 residents were being evacuated.

(6月24至27日) 熱帶風暴浪卡吹襲菲律賓東部和中部，造成至少 9 人死亡，5 人受傷，7 人失蹤。浪卡於南海轉向北移，於 27 日凌晨在廣東惠東縣平海鎮登陸，距離香港約 60 公里。雖然本港發出三號強風信號，但市面風勢微弱，部分市民如常活動。

(Jun 24-27) Tropical storm Nangka swept through the eastern and central parts of the Philippines, killing at least 9 and injuring 5, with another 7 missing. Nangka turned northwards in the South China Sea, and made landfall in Guangdong on June 27, 60 kilometres from Hong Kong. Although the Strong Wind Signal was issued in the territory, winds were light and citizens' activities were largely unaffected.

(1月28日) 澳洲 1 月底受熱浪影響，南部部份地區連續多日高溫超過 40 度，維多利亞州部分地區更錄得 48 度高溫，打破歷年紀錄。

(Jan 28) A heat wave affected southeastern Australia in late January; some southern areas recorded temperatures in excess of 40 degrees for a few days, and a record high of 48 degrees was recorded in Victoria.

(12月9日) 天文台指出，受全球變暖和本地城市化影響， 2000 至 2009 年一至十一月的平均氣溫為 24.0 度，以年代計算是有紀錄以來最高；2009 年頭 11 個月於天文台總部的平均氣溫為 24.1 度，是自 1884 年有紀錄以來的第五高。

(Dec 9) The Observatory stated that due to global warming and urbanization, the mean temperature for the first eleven months during 2000 and 2009 is 24.0 degrees, the highest in any decade since records began. Meanwhile, the mean temperature for the first eleven months this year is 24.1 degrees, the fifth highest since 1884.

(1月8日) 哥斯達黎加出現 150 年來最猛烈的地震，造成 34 死 91 傷 56 失蹤。

(Jan 8) Strongest earthquake in 150 years hit Costa Rica, causing 34 deaths and 91 people were injured. 56 people were reported missing.

(9月23日) 澳洲東部地區遭受沙塵暴侵襲，影響新南威爾斯州、昆士蘭州及維多利亞州，是 70 年來最大的一場沙塵暴，共造成數千萬澳元的損失。眾多城市天空變成紅色一片，悉尼的空氣污染指數更一度達 4164 ，比正常高 1500 倍。

(Sep 23) The cities of Canberra, Sydney and Brisbane in Australia were covered by a dust storm, the worst in at least 70 years. Losses amounted to tens of millions of Australian dollars. Many cities were turned red as a result, with Sydney's Air Quality Index reaching 4164, 1500 times above normal.

(4月21日) 歐洲天文學家宣布在天秤座發現紅矮星格利澤 581 的一顆行星格利澤 581e，是目前發現的質量大小和地球最接近的太陽系外行星，但它處於適居帶外，且不太可能擁有大氣層。

(Apr 21) The smallest confirmed extrasolar planet, Gliese 581e, was discovered. Its mass is closest to that of the Earth among those discovered, but the planet is situated outside of the habitable zone and possession of an atmosphere is unlikely.

(10月18日) 颶風 Rick 於東太平洋增強為五級颱風 (風速達每小時 155 海里 / 285 公里)，成為該區十年來最強的熱帶氣旋，但未能成為本年全球最強的氣旋。

(Oct 18) Hurricane Rick strengthened to a Category 5 storm with winds reaching 155 knots (285 kilometres per hour), becoming the strongest hurricane in a decade in the eastern Pacific Ocean. However, it failed to become the strongest tropical cyclone globally this year.

(6月21日) 減弱為熱帶風暴的氣旋蓮花在中國福建省晉江市東石鎮登陸，造成至少 1 人死亡、 2 人失蹤，廣東、福建兩省經濟損失 6.69 億元。蓮花亦令天文台發出本年度的首個熱帶氣旋警告信號。

(Jun 21) A weakened tropical storm Linfa made landfall in Fujian on June 21, killing at least 1 person and two others were missing. The estimated losses in Guangdong and Fujian provinces amounted to 669 million yuan. Linfa also necessitated the first tropical cyclone signal this year in Hong Kong.

(10月17日) 馬爾代夫總統納希德率領內閣成員，潛入 5 米深水底開會，呼籲全球正視氣候暖化問題。

(Oct 17) The government of the Maldives, including President Mohamed Nasheed, held the world's first underwater Cabinet meeting, to highlight the threat of global warming.

(12月19日) 台灣花蓮外海發生一次 6.3 級 (當地測得 6.8 級) 地震，為至今本年度當地最強的一次，造成最少 15 人傷。本港天文台亦錄得是次地震，並接獲數名市民的報告。天文台指出，是次地震於香港的烈度為修定麥加利地震烈度表的第二度。

(Dec 19) A 6.3 magnitude earthquake occurred in seas near Hualien, Taiwan (Magnitude 6.8 according to local authorities), the strongest so far this year in Taiwan. At least 15 people were injured in this event. The HK Observatory also detected this earthquake, and received reports from the public about the tremor. The Observatory indicated that this earthquake inflicted a level II intensity shock on the Modified Mercalli Scale in Hong Kong.

(2月2日) 英國和愛爾蘭遭遇 18 年來最大的降雪，導致兩國交通系統大面積癱瘓，並有3000多所學校停課。

(Feb 2) The heaviest snowfall in 18 years disrupted UK transportation and communications. More than 3000 schools had their classes suspended.

(12月4日) 尼泊爾政府官員在珠穆朗瑪峰召開內閣會議，喚起國際社會對氣候變化的關注。

(Dec 4) Nepal's cabinet met on Mount Everest to highlight the impact of climate change in the Himalayas.

(3月7日) 美國太空總署開普勒太空望遠鏡在佛羅里達州卡納維拉爾角空軍基地發射升空，成為世界首個專門用於搜尋太陽系外類地行星的航天器。

(Mar 7) NASA successfully launched the Kepler Telescope in Florida, which became the first telescope designed to discover Earth-like planets orbiting other stars.

(4月6日) 意大利中部地區發生黎克特制 5.8 級 (矩震級 6.3 級) 強烈地震，震央位於阿布魯佐大區首府拉奎拉，造成 290 人死亡，1500 人受傷。

(Apr 6) 290 people were killed and 1,500 injured in a severe earthquake near L'Aquila, Italy, which registered 5.8 on the Richter scale and 6.3 on the moment magnitude scale.

(10月7日) 美國弗吉尼亞大學和馬利蘭大學的科學家利用斯皮策太空望遠鏡發現一個巨型土星環，為迄今發現的太陽系中最大的行星環。

(Oct 7) The discovery of a new ring around Saturn was announced. The discovery was made by Anne J. Verbiscer and Michael F. Skrutskie (of the University of Virginia) and Douglas P. Hamilton (of the University of Maryland, College Park).

(1月26日) 時值大年初一，印度洋部分地方和印尼西部看到一次日環食；香港雖然於偏食帶上，但由於天氣欠佳，本港與是次日食緣慳一面。

(Jan 26) An annular eclipse occurred on the first day of the Lunar New Year which was visible in parts of Indian Ocean and western Indonesia. Although situated within the region of partial eclipse, Hong Kong's cloudy weather that day prevented citizens from viewing the event.

(2月24日) 由台灣國立中央大學鹿林天文台觀測員和廣東中山大學學生在 2007 年合作發現的鹿林彗星移動到離地球最近的位置，成為一顆肉眼可見的彗星。

(Feb 24) Comet Lulin, the first comet discovered at Taiwan, arrived at perigee for observers on Earth on February 24.

(1月10日) 熱帶低氣壓 04F 為斐濟帶來大雨，導致 11 人死亡，超過 6000 人無家可歸。

(Jan 10) Flooding caused by Tropical Depression 04F killed eleven people and displaced more than 6,000 in Fiji.

(2月9日) 世界大部分地區 (包括香港) 於今天見到一次半影月食。

(Feb 9) A penumbral eclipse occurred today, and was visible in most parts of the world.

(7月2日) 歐洲航天局普朗克衛星飛抵運行軌道，其溫度通過冷卻系統下降到零下 273.05 攝氏度，成為宇宙間有史以來溫度最低的物體。

(Jul 2) The detectors of Planck's High Frequency Instrument reached a low operational temperature of -273.05°C, making them the coldest known objects in space.

(11月) 蘇格蘭南部及英格蘭部分地區遭受大雨影響，多處地方水浸。這是英國於 1914 年有紀錄以來最濕的 11 月。

(Nov) Southern Scotland and parts of England were affected by heavy rains. November 2009 is the wettest since records began in 1914.

(2009年) 本年西北太平洋出現三個五級超級颱風 : 彩雲 (9月)、茉莉 (9-10月) 和 妮妲 (11-12月)。

(2009) Three category 5 super typhoons formed in the northwestern Pacific Ocean ths year. They are CHOI-WAN (Sep), MELOR (Sep-Oct) and NIDA (Nov-Dec)

(11月23日) 已使用超過 10 年的 QuikScat 衛星天線停止轉動。QuikScat 於過去的 10 年為氣象學家提供海面風向和風速分布，以方便相關分析。

(Nov 23) The antenna of the 10-year-old QuikScat satellite stopped spinning. It had been providing meteorologists with valuable wind direction and speed information over oceans.

(11月) [?] 十一月的溫差紀錄達 11 度。

(Nov) [?] Temperature difference in the month reached 11 degrees.