Bruger:Brol/sandkasse

KlimaRediger

 
Sydney Harbour Bridge under støvstorm i 2009.

Sydney har et fugtigt subtropisk klima (Köppens klimaklassifikation: Cfa) med varme eller meget varme somre og milde vintre. Regnen er fordelt over hele året. Vejret modereres af det nærliggende hav, og mere ekstreme temperaturer måles i de vestlige forstæder end i byens centrum. De varmeste måneder er januar og februar med en gennemsnitstemperatur ved vejrstationen Observatory Hill i centrum, der ligger på 20,0 °C i januar og 19,9 °C i februar.[1] Gennemsnitligt har 19,4 dage om året en temperatur på 30 °C eller over.[1]

Om vinteren falder temperaturen sjældent under 5 °C i kystområderne. Den koldeste måned er juli med gennemsnitstemperaturer på 8,9 °C – 17,9 °C.[1] Nedbør er jævnt fordelt over hele året, men dog lidt højere i årets første halvdel. Den gennemsnitlige nedbørsmængde, som kun varierer lidt, er 1150 mm. I gennemsnit regner det 134,4 dage om året.[1] Snefald blev sidst rapporteret i Sydney City i 1836, men en byge af graupel (blød hagl) i juli 2008, som mange troede var sne, har øget muligheden for, at det heller ikke var sne, der faldt i 1836.[2][3] Ekstreme temperaturer spænder fra 45,8 °C målt den 18. januar 2013 til 2,1 °C den 22. juni 1932 ved Observatory Hill.[4] Ved vejrstationen ved Sydney Airport, som også er kystnær, er der målt 46,4 °C og -0,1 °C.[5] I januar 2020 blev der i den vestlige forstad Penrith målt 48,9 °C.[6]

Australiens Bureau of Meteorology har rapporteret at somrene fra 2002 til 2005 var de varmeste i Sydney siden målingerne startede i 1859.[7] Sommeren 2007–2008 var til gengæld den koldeste siden 1996-1997 og var den første sommer i dette årtusinde, som var koldere end gennemsnittet.[8] I 2009 gav en varm sommer betingelserne for en alvorlig støvstorm i det østlige Australien, som også ramte Sydney.[9][10] Sommeren 2012-13 var varm og våd og der blev slået varmerekorder over hele byen i januar.[11] De efterfølgende somre var alle varmere end gennemsnittet indtil 2020-21, som var koldere end normalt.

Havets gennemsnitstemperatur er over 20,8 °C og det månedlige gennemsnit strækker sig fra 18,2 °C i august til 23,5 °C i februar.[12]

El Niño, den sydlige oscillation, spiller en afgørende rolle for Sydney. Den varme fase giver tørke og skovbrande, medens den kolde storme og oversvømmelser. Mange af forstæderne i byens udkant har været ramt af skovbrande, som hyppigst forekommer forår og sommer. Byen rammes sjældent direkte af cykloner, men er udsat for storme og kraftige haglbyger. I 1999 blev Sydney ramt af et kraftigt haglvejr, som forårsagede store skader i centrum og de østlige forstæder. De største hagl målte mindst 9 cm i diameter og forårsagede forsikringsskader på omkring A$ 1,7 milliarder på mindre end 5 timer.[13]

Klimadata for Sydney (Observatory Hill), gennemsnit 1991-2000, ekstremer siden 1861
Måned Jan Feb Mar Apr Maj Jun Jul Aug Sep Okt Nov Dec År

Rekord maks 45,8 42,1 39,8 35,4 30,0 26,9 26,5 31,3 34,6 38,2 42,8 42,2 45,8

Maks °C 27,0 26,8 25,7 23,6 20,9 18,2 17,9 19,3 21,6 23,2 24,2 25,7 22,8

Min °C 20,0 19,9 18,4 15,3 12,3 10,0 8,9 9,7 12,3 14,6 16,6 18,4 14,7

Rekord min °C 10,6 9,6 9,3 7,0 4,4 2,1 2,2 2,7 4,9 5,7 7,7 9,7 2,1

Nedbør mm 91,1 131,5 117,5 114,1 100,8 142,0 80,3 75,1 63,4 67,7 90,6 73,0 1.147,1

Dage med nedbør 8,2 9,0 10,1 7,9 7,9 9,3 7,2 5,6 5,8 7,6 8,7 7,9 95,2

Månedlige solskinstimer 232,5 205,9 210,8 213,0 204,6 171,0 207,7 248,0 243,0 244,9 222,0 235,6 2.639

Kilde 1: Klimagennemsnit for Sydney Observatory Hill[1] [4]
Kilde 2: Solskinstimer for Sydney Airport[14]



At Sydney's primary weather station at Observatory Hill, extreme temperatures have ranged from 45,8 °C (114,4 °F)* on 18 January 2013 to 2,1 °C (35,8 °F)* on 22 June 1932.[15][16][17] An average of 14.9 days a year have temperatures at or above 30 °C (86 °F) in the central business district (CBD).[6] In contrast, the metropolitan area averages between 35 and 65 days, depending on the suburb.[18] The highest minimum temperature recorded at Observatory Hill is 27,6 °C (82 °F)*, on 6 February 2011, while the lowest maximum temperature is 7,7 °C (46 °F)*, recorded on 19 July 1868.[6] The hottest day in the Sydney metropolitan area occurred in Penrith on 4 January 2020, where a high of 48,9 °C (120,0 °F)* was recorded.[19] The average annual temperature of the sea ranges from 18,5 °C (65,3 °F)* in September to 23,7 °C (74,7 °F)* in February.[20] Sydney has an average of 7.2 hours of sunshine per day[21] and 109.5 clear days annually.[22]

The weather is moderated by proximity to the ocean, and more extreme temperatures are recorded in the inland western suburbs.[6] Sydney experiences an urban heat island effect.[23] This makes certain parts of the city more vulnerable to extreme heat, including coastal suburbs.[23][24] In late spring and summer, temperatures over 35 °C (95 °F) are not uncommon,[25] though hot, dry conditions are usually ended by a southerly buster,[26] a powerful southerly that brings gale winds and a rapid fall in temperature.[27] Since Sydney borders the Great Dividing Range, it can occasionally experience dry, westerly Föhn-like winds usually between winter and spring, as it lies on the leeward side of the ranges, thereby elevating fire danger in the region.[28][29] Due to the inland location, frost is recorded early in the morning in Western Sydney a few times in winter. Autumn and spring are the transitional seasons, with spring showing a larger temperature variation than autumn.[30]

The Bureau of Meteorology reported that 2002 to 2005 were the warmest summers in Sydney since records began in 1859.[31] The summer of 2007–08, however, proved to be the coolest since 1996–97 and is the only summer this century to be at or below average in temperatures.[32] In 2009, dry conditions brought a severe dust storm towards eastern Australia.[33][34] The El Niño–Southern Oscillation, the Indian Ocean Dipole and the Southern Annular Mode[35][36] play an important role in determining Sydney's weather patterns: drought and bushfire on the one hand, and storms and flooding on the other, associated with the opposite phases of the oscillation. Many areas of the city bordering bushland have experienced bushfires, which tend to occur during the spring and summer.[37][38]

 
A summer thunderstorm over the city taken from Potts Point, 1991.

The rainfall has a moderate to low variability and it is spread through the months, though it has been erratic in recent times.[39][40] Even in its months of highest rainfall, Sydney has relatively few rainy days, with an average mean of 7 to 8 rainy days per month on the 1 mm (0,04 in) threshold. Precipitation is usually higher in late summer through to early winter when the subtropical ridge is to the south of Australia, permitting easterly winds to dominate, and lower in late winter to early spring when the subtropical ridge is to the north, as it brings dry winds from the continent's interior towards the city, since it rotates counter-clockwise.[35][41][6][42] From 1990 to 1999, Sydney received around 20 thunderstorms per year.[43] In late autumn and winter, east coast lows may bring large amounts of rainfall, especially in the CBD.[44]

In spring and summer, black nor'easters are usually the cause of heavy rain events, though other forms of low-pressure areas may also bring heavy deluge and afternoon thunderstorms.[45] Depending on the wind direction, summer weather may be humid or dry, with the late summer/autumn period having a higher average humidity and dewpoints than late spring/early summer. In summer, most rain falls from thunderstorms and in winter from cold fronts.[46] Snowfall was last reported in the Sydney City area in 1836, while a fall of graupel, or soft hail, was mistaken by many for snow, in July 2008.[47] The city is rarely affected by cyclones, although remnants of ex-cyclones do affect the city. The city is also prone to severe storms. One such storm was the 1999 hailstorm, which produced massive hailstones up to Skabelon:Cvt in diameter.[13]

Skabelon:Sydney weatherbox

  1. ^ a b c d e "Sydney Observatory Hill. Climate statistics for Australian locations. 1991-2020". Bureau of Meteorology. Hentet 23. februar 2021. 
  2. ^ "Sydney winter not snow, just hail". Sydney Morning Herald. Hentet 15. november 2013. Mr Zmijewski doubted the 1836 snow report, saying weather observers of the era lacked the expertise of today. "We are almost in the sub-tropics in Sydney", he said. 
  3. ^ MacDonnell, Freda. Thomas Nelson (Australia) Limited, 1967. Before King's Cross
  4. ^ a b "Sydney Observatory Hill. Climate statistics for Australian locations. All years of record". Bureau of Meteorology. Hentet 23. februar 2021. 
  5. ^ "Sydney Airport AMO. Climate statistics for Australian locations.". Bureau of Meteorology. Hentet 13. december 2013. 
  6. ^ a b c d e "Greater Sydney in 2020". Bureau of Meteorology. Hentet 24.februar 2021.  Tjek datoværdier i |access-date= (hjælp) Fodnotefejl: Ugyldigt <ref> tag; navnet "acn" er defineret flere gange med forskelligt indhold
  7. ^ Sydney has coldest June in 24 years in Sydney Monthly Climate Summary – NSW Regional Office, Bureau of Meteorology. Retrieved 21 October 2007.
  8. ^ "Sydney – Greater Sydney in 2008". Bom.gov.au. 5. januar 2009. Hentet 10. februar 2012. 
  9. ^ "Sydney in 2009". Bom.gov.au. 4. januar 2010. Hentet 10. februar 2012. 
  10. ^ "Sydney in 2010". Bom.gov.au. 4. januar 2011. Hentet 10. februar 2012. 
  11. ^ "Sydney in Summer 2013". Australian Bureau of Meteorology. Hentet 6. marts 2021. 
  12. ^ "Sydney Climate (Australia)". Climate-Data.org. Hentet 2. marts 2021. 
  13. ^ a b "The Sydney Hailstorm – 14 April 1999". Bureau of Meteorology. Hentet 5. oktober 2006.  Fodnotefejl: Ugyldigt <ref> tag; navnet "autogenerated1999" er defineret flere gange med forskelligt indhold
  14. ^ "Sydney Airport. Climate statistics for Australian locations.". Bureau of Meteorology. Hentet 23. februar 2021. 
  15. ^ Skabelon:BoM Aust stats
  16. ^ Bureau of Meteorology. 2006. Climate summary for Sydney, January 2006
  17. ^ Creagh, Sunanda. "Sydney smashes temperature records but heatwave nearly over". The Conversation. The Conversation Media Group. Hentet 21 January 2013. 
  18. ^ Torok, S. and Nicholls, N. 1996. A historical annual temperature dataset for Australia. Aust. Met. Mag., 45, 251–60.
  19. ^ "Penrith hits record temperature of 48.9C as heatwave strikes NSW". Daily Telegraph. Hentet 6 January 2020. 
  20. ^ Sydney Sea Temperature – seatemperature.org
  21. ^ "Climate statistics for Australian locations Sydney Airport AMO". Bureau of Meteorology. 
  22. ^ "Sydney (Observatory Hill) Period 1991-2020". Bureau of Meteorology. Hentet 14 April 2020. 
  23. ^ a b "Sydney area an 'urban heat island' vulnerable to extreme temperatures". The Sydney Morning Herald. 14 January 2016. Hentet 14 January 2016. 
  24. ^ Santamouris, Mat; Haddad, Shamila; Fiorito, Francesco; Osmond, Paul; Ding, Lan; Prasad, Deo; Zhai, Xiaoqiang; Wang, Ruzhu (2017). "Urban Heat Island and Overheating Characteristics in Sydney, Australia. An Analysis of Multiyear Measurements". Sustainability. University of New South Wales. 9 (5): 712. doi:10.3390/su9050712. 
  25. ^ "Special Climate Statement 43 – extreme heat in January 2013" (PDF). Bureau of Meteorology. 1 February 2013. Hentet 2 February 2013. 
  26. ^ Batt, K, 1995: Sea breezes on the NSW coast, Offshore Yachting, Oct/Nov 1995, Jamieson Publishing.
  27. ^ ""Southerly Buster" Relieves City.". The Sydney Morning Herald. National Library of Australia. 17 December 1953. s. 1. Hentet 27 March 2015. 
  28. ^ Sharples, J.J. Mills, G.A., McRae, R.H.D., Weber, R.O. (2010) Elevated fire danger conditions associated with foehn-like winds in southeastern Australia. Journal of Applied Meteorology and Climatology.
  29. ^ Sharples, J.J., McRae, R.H.D., Weber, R.O., Mills, G.A. (2009) Foehn-like winds and fire danger anomalies in southeastern Australia. Proceedings of the 18th IMACS World Congress and MODSIM09. 13–17 July, Cairns.
  30. ^ MacDonnell, Freda. Thomas Nelson (Australia) Limited, 1967. Before King's Cross
  31. ^ Sydney has coldest June in 24 years in Sydney Monthly Climate Summary – NSW Regional Office, Bureau of Meteorology. Retrieved 21 October 2007.
  32. ^ "Sydney – Greater Sydney in 2008". Bom.gov.au. 5 January 2009. Hentet 10 February 2012. 
  33. ^ "Sydney in 2009". Bom.gov.au. 4 January 2010. Hentet 10 February 2012. 
  34. ^ "Sydney in 2010". Bom.gov.au. 4 January 2011. Hentet 10 February 2012. 
  35. ^ a b "Southern Annular Mode: The climate 'influencer' you may not have heard of". ABC News. Hentet 29 September 2020. 
  36. ^ "Special Climate Statement 71—severe fire weather conditions in southeast Queensland and northeast New South Wales in September 2019" (PDF). Bureau of Meteorology. 24 September 2019. Hentet 5 January 2020. 
  37. ^ "The 10 Sydney regions most exposed to bushfire risk". Sydney Morning Herald. Hentet 7 November 2020. 
  38. ^ "The Sydney suburbs in bushfire danger on a day of 'catastrophic' conditions". News.com.au. Hentet 7 November 2020. 
  39. ^ "Sydney future: high temps, erratic rain". The Sydney Morning Herald. 
  40. ^ "Commuters in Sydney and eastern NSW brace for erratic weather". News.com.au. 
  41. ^ Drosdowsky, Wasyl (16 March 2005). "The latitude of the subtropical ridge over Eastern Australia: TheL index revisited". INTERNATIONAL JOURNAL OF CLIMATOLOGY, Bureau of Meteorology Research Centre. 25 (10): 1291-1299. Bibcode:2005IJCli..25.1291D. doi:10.1002/joc.1196. Hentet 29 September 2020. 
  42. ^ Australian Bureau of Meteorology. 2005. Ellyard, D. 1994. Droughts and Flooding Rains. Angus & Robertson ISBN 0-207-18557-3
  43. ^ "Average annual thunder-day map". Arkiveret fra originalen 12 February 2017. Hentet 17 March 2017. 
  44. ^ "About East Coast Lows". Bureau of Meteorology. Hentet 6 April 2013. 
  45. ^ "Black Nor-Easter.". The Sydney Morning Herald. National Library of Australia. 30 October 1911. s. 7. Hentet 27 March 2015. 
  46. ^ Power, S., Tseitkin, F., Torok, S., Lavery, B., Dahni, R. and McAvaney, B. 1998. Australian temperature, Australian rainfall and the Southern Oscillation, 1910–1992: coherent variability and recent changes. Aust. Met. Mag., 47, 85–101
  47. ^ "Sydney winter not snow, just hail". Sydney Morning Herald. 27 July 2008. Hentet 15 November 2013. Mr Zmijewski doubted the 1836 snow report, saying weather observers of the era lacked the expertise of today. "We are almost in the sub-tropics in Sydney", he said.