Severe weather events or extreme weather events in Sydney, include hailstorms, thunderstorms, gale, bushfires, heatwaves, drought, and flash flooding (caused by East coast lows or black nor'easters). Sydney is rarely affected by cyclones, although remnants of cyclones do affect the city.
Global warming has increased the chances of extreme rain and flash floods in Sydney recently, such as the notable 2021 and 2022 flood events.Turbulent La Nina season makes it even harder to predict the weather Sydney Morning Herald 21 January 2022. Nevertheless, destructive heavy rainfall events have been recorded in the Sydney area since records began in the 18th century.
Annually, coastal Sydney sees five heat-related deaths per 100,000 people while the western suburbs see 14 per 100,000.‘Heat dome’ surrounding Australian CBDs leave suburbs to scorch by Benedict Brook from News.com.au. Retrieved 25 November 2020. Heat-related deaths in the city were common in the late 19th and early 20th century period (due to lack of air conditioners) where several individual cases were reported.
Temperatures 1800s–1990s 5 January 1863 is Sydney's first recorded day, when the mercury hit at Sydney's Observatory Hill. On 19 July 1868, Observatory Hill recorded a maximum temperature of just 7.7 °C (45.9 °F), the lowest daily maximum temperature on record for Sydney. During January 1896, a state wide heatwave blasted through NSW and caused the mercury in Sydney to hit on the 6th and on the 13th, this ended Sydney's longest streak of days under which lasted from 14 January 1870 – 5 January 1896. The heatwave also caused the death of 437 people across eastern Australia.https://coherence.com.au/curlew/2022/08/deadly-aust-heat-wave-of-1896/ On 10 January 1929, extreme heat kills thousands of fowls on poultry farms in the city as temperatures rose to . On 11 June 1931, Sydney registered its warmest June day on record at , this was more than 10 degrees above the average June temperature at the time.http://www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=122&p_display_type=dailyDataFile&p_startYear=1931&p_c=-872851191&p_stn_num=066062 On 6 March 1938, Richmond in Sydney's north western area recorded the highest autumn temperature in the city's metropolitan area, shattering the previous record by almost 3C when it hit .http://www.bom.gov.au/climate/averages/tables/cw_067033_All.shtml On 1 April 1945, Sydney experienced its coldest April day in 86 years, with a minimum temperature of 10.8 °C (51.5 °F) and a maximum of 18.3 °C (64.9 °F). In 1972, Sydney recorded its coldest August day on record, with a maximum temperature of 9.1 °C (48.4 °F). On 1 February 1977, Sydney was hit by a massive heatwave that sent record breaking temperatures never seen in the month of February. Temperatures skyrocketed to at Liverpool, more than 2 degrees hotter than anywhere else in Sydney. Other places that broke heat records at the time were Sydney CBD's second hottest day at , Bankstown , and Richmond which stood as the hottest February days at both Bankstown and Richmond for 40 years.http://www.bom.gov.au/cgi-bin/climate/extremes/daily_extremes.cgi?period=%2Fcgi-bin%2Fclimate%2Fextremes%2Fdaily_extremes.cgi&climtab=tmax_high&area=nsw&year=1977&mon=2&day=1 On 3 July 1984, Sydney CBD recorded a maximum temperature of just . On 27 July 1986, the temperature at Observatory Hill fell to 3.1 °C (37.6 °F), making it Sydney's coldest July morning in the instrumental record. The highest recorded minimum temperature in Sydney was registered at Orchard Hills, New South Wales, a suburb right beneath Penrith, at on 9 January 1983.http://www.bom.gov.au/cgi-bin/climate/extremes/daily_extremes.cgi?period=%2Fcgi-bin%2Fclimate%2Fextremes%2Fdaily_extremes.cgi&climtab=tmin_high&area=nsw&year=1983&mon=1&day=9 On 21 October 1988, Camden, Richmond and Parramatta recorded the first and only instance of a during the month of October in Greater Sydney. Camden hitting , Richmond hitting and Parramatta hitting .http://www.bom.gov.au/climate/averages/tables/cw_068192_All.shtmlhttp://www.bom.gov.au/climate/averages/tables/cw_067033_All.shtmlhttp://www.bom.gov.au/climate/averages/tables/cw_066124_All.shtml
1990s–2000s On 26 August 1995, Sydney CBD recorded its hottest winter day on record at . On 15 January 2001, Penrith hit and Prospect Reservoir hit as a result of a statewide heatwave. This was hottest day at both stations until 2013 and Greater Sydney's hottest day in 62 years. Sydney CBD's temperature was only that day.http://www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=122&p_display_type=dailyDataFile&p_startYear=2001&p_c=-898303023&p_stn_num=067019http://www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=122&p_display_type=dailyDataFile&p_startYear=2001&p_c=-872831319&p_stn_num=066062 From 25–26 November 2002, Sydney CBD recorded two days in a row with a maximum temperature of , its first instance in Spring. Greater Sydney had the top three hottest places on earth that day, Penrith , Parramatta and Richmond .http://www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=122&p_display_type=dailyDataFile&p_startYear=2002&p_c=-872831319&p_stn_num=066062http://www.bom.gov.au/cgi-bin/climate/extremes/daily_extremes.cgi?period=%2Fcgi-bin%2Fclimate%2Fextremes%2Fdaily_extremes.cgi&climtab=tmax_high&area=aus&year=2002&mon=11&day=25 From 18 January – 30 January 2003, Greater Sydney recorded four days above . Maximum temperatures during these 12 days were on the 18th at Liverpool, on the 21st at Penrith, on the 26th at Penrith, and on the 30th at Badgerys Creek. This weather pattern was never seen before at the time.http://www.bom.gov.au/cgi-bin/climate/extremes/daily_extremes.cgi?period=%2Fcgi-bin%2Fclimate%2Fextremes%2Fdaily_extremes.cgi&climtab=tmax_high&area=nsw&year=2003&mon=1&day=18http://www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=122&p_display_type=dailyDataFile&p_startYear=2003&p_c=-900824704&p_stn_num=067113http://www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=122&p_display_type=dailyDataFile&p_startYear=2003&p_c=-900690483&p_stn_num=067108 On 21 February 2004, Penrith recorded Greater Sydney's latest instance of a day, hitting that exact temperature.http://www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=122&p_display_type=dailyDataFile&p_startYear=2004&p_c=-900824704&p_stn_num=067113 On 13 October 2004, Sydney CBD and Sydney Airport recorded their hottest day in the month in october, with at the airport and at the CBD, both defeating a record set in 1942 by almost a degree.http://www.bom.gov.au/cgi-bin/climate/extremes/daily_extremes.cgi?climtab=tmax_high&area=nsw&year=2004&mon=10&day=13 The morning of 7 August 2005 was the coldest August morning ever seen in Greater Sydney, when the temperature in Richmond plummeted to , the previous August low record was in 1941, 0.4C warmer.http://www.bom.gov.au/climate/averages/tables/cw_067105_All.shtmlhttp://www.bom.gov.au/climate/averages/tables/cw_067033_All.shtml 1 January 2006 was Sydney's hottest New Year's Day ever recorded. Sydney Airport and Parramatta had their hottest days on record at the time, at the Airport and at Parramatta, beating their records dating back to November 1982 and January 2003.http://www.bom.gov.au/climate/current/annual/nsw/archive/2006.sydney.shtml On 16 November 2006, Observatory Hill recorded a minimum temperature of 11.4 °C (52.5 °F), making it Sydney's coldest November night in more than a century. On 17 July 2007, Sydney CBD recorded its coldest morning since 1986 and its coldest morning so far in the 21st century, when the temperature dipped to . Temperatures west of the CBD dipped to at Badgerys Creek.http://www.bom.gov.au/climate/current/month/nsw/archive/200707.sydney.shtml In the summer of 2007–2008, Sydney CBD didn't experience a singular day over , only the third instance of it happening.http://www.bom.gov.au/climate/current/season/nsw/archive/200802.sydney.shtml On 23 October 2008, Observatory Hill recorded a maximum temperature of just 14.9 °C (58.8 °F), making it Sydney's coldest October day in 30 years. November 2009 was the hottest November in the CBD in 115 years and the hottest November on record for most of Greater Sydney. The average maximum temperature at the CBD and Penrith were and . The highest temperatures recorded during the month were at Sydney Airport and at Penrith. Sydney CBD registered its then second hottest spring day at .http://www.bom.gov.au/climate/current/month/nsw/archive/200911.sydney.shtml
2010s
From 30 January to 6 February 2011, Western Sydney endured eight days in a row above along with 5 nights in a row above . 6 days reached with a peak temperature of on 5 February.http://www.bom.gov.au/climate/current/month/nsw/archive/201102.sydney.shtmlhttp://www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=122&p_display_type=dailyDataFile&p_startYear=2011&p_c=-900826312&p_stn_num=067113 Along with that was Sydney CBD's warmest night within its 160 years of record keeping, at on 6 February. On 23 August 2012, a foehn effect caused Sydney to record its 3rd warmest August day on record where it reached at the CBD and at Sydney Airport.Sydney records third warmest August day on record By Stephanie Gardiner from Sydney Morning Herald. 23 August 2012. Retrieved 3 March 2022. The highest recorded maximum temperature at Observatory Hill was on 18 January 2013 during a prolonged heat wave across Australia from early December 2012 to late January 2013. July 2013 was the warmest on record, with an average maximum temperature of , which is above the historical average. This was due to persistent, warm northerly winds and clear conditions. In September 2013, temperatures were above average and the city had over seven days where temperatures reached , making it more similar to November's weather pattern. On 23 November 2014, Sydney recorded its hottest spring day, with in Richmond and in Penrith, breaking the previous 1982 record by 1.7C (3.6F). Meanwhile, Sydney CBD remained much cooler at a 15.2C (27.4F) difference from Richmond.http://www.bom.gov.au/climate/current/month/nsw/archive/201411.sydney.shtml October 2015 had the warmest nights on record, which were above average. In the summer of 2016–17, Sydney CBD experienced a record-breaking of 26 days where temperatures were above and 11 days of temperatures higher than , with record numbers of days above recorded in western Sydney including 11 days at Richmond, in addition to the most warm nights on record. On 10–11 February 2017, a heatwave swept through NSW, breaking multiple records, including parts of Sydney's hottest February days. Parramatta and Bankstown hit 44.5 °C (112.1 °F) on the 10th, surpassing records from 1979 and 1977. Sydney Airport reached 42.9 °C (109.2 °F), breaking its 1980 record. On the 11th, Sydney's west was hit harder; Camden Airport recorded 45.6 °C (114.1 °F), Penrith 46.9 °C (116.4 °F), and Richmond 47.0 °C (116.6 °F), all surpassing previous records, some by significant margins.
On 7 January 2018, Sydney was the hottest place on Earth as Penrith reached . In April 2018, Sydney had the longest running hot spell for that month with nine consecutive days of temperatures reaching . Furthermore, the airport and parts of the western suburbs also broke heat records in that month. January 2019 was the hottest month on record for most of Sydney. The average maximum temperature at the airport was , 4 °C above average with 19 calendar days in a row above 20 °C (12–31 January). The average maximum temperature at Richmond was and recorded a whopping 15 days above that month. Highs of were recorded on 5 and 17 January at Penrith.http://www.bom.gov.au/climate/current/month/nsw/archive/201901.sydney.shtml#:~:text=Greater%20Sydney%20in%20January%202019,most%20sites%20across%20Greater%20Sydney. On New Years Eve 2019, Penrith recorded its hottest December day when the temperature peaked at 46.3 °C (115 °F).
2020s–present