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|caption = The high featuring a [[anticlockwise]] rotation around an oval area of clear skies.
|area of occurrence=[[Great Australian Bight]] in [[Southern Australia]] (extending to [[Bass Strait]] and the [[Tasman Sea]] in the east)
|season=November–May
|effect= *Dry conditions with little rainfall and summer [[drought]] in the west and south
* Moist conditions in the southeast coast, particularly east of the [[Great Dividing Range]]
}}
The '''Australian High''', also known as the '''Great Australian Bight High''' or '''Southern Australian High''', is a large semi-permanent [[high pressure system|high pressure]] area or subtropical [[anticyclone]] that stretches from the [[Great Australian Bight]] in [[Western Australia]] and [[South Australia]] to the southern [[Victoria (state)|Victorian]] coastline on [[Bass Strait]] and the east coast of [[Tasmania
In summer, it typically sits over [[southern Australia]], where it generally provides dry weather in the proximate region. In winter it normally moves north, thus permitting [[cold front]]s and [[low pressure system]]s to relocate up from the Great Australian Bight and bring rainfall to most parts of southern Australia.<ref name = BOM>[http://www.bom.gov.au/climate/updates/articles/a025.shtml#:~:text=The%20subtropical%20ridge%20is%20a,on%20the%20climate%20of%20Australia. Subtropical ridge leaves us high and dry this June] [[Bureau of Meteorology]]. July 2017.</ref>
==Description==
[[File:High Pressure.jpg|thumb|left|The Australian High west of Tasmania over the [[Indian Ocean]]]]
The Australian High tends to follow the seasonal variation in [[position of the sun]]; it is strongest and most persistent during the southern hemisphere summer and weakest during winter when it shifts towards the interior of Australia, as the [[westerlies|westerly]] [[frontal system]]s becomes more active in the region around the Bight, thereby allowing cold fronts and low-pressure systems to perforate the southern states.<ref name = prevention>[https://www.preventionweb.net/news/stalled-weather-how-stuck-air-pressure-systems-drive-floods-and-heatwaves STALLED WEATHER: HOW STUCK AIR PRESSURE SYSTEMS DRIVE FLOODS AND HEATWAVES] by Steve Turton from PreventionWeb.net. 3 March 2022</ref> This high-pressure block exhibits anticyclonic behaviour, circulating the air clockwise. It remains almost stationary for an prolonged period over the Bight, hence obstructing the typical easterly procession of weather systems across southern Australia.<ref>[https://www.abc.net.au/news/2018-08-14/southern-annular-mode-and-how-it-affects-our-weather/10106134 Southern Annular Mode: The climate 'influencer' you may not have heard of] By Kate Doyle from [[ABC TV (Australian TV channel)|ABC]]. 14 August 2018. Retrieved 7 April 2022.</ref>
The High can stretch thousands of kilometers across the [[Bight (geography)|Bight]], and may move eastwards towards [[Tasmania]] towards the [[South Pacific Ocean]]. This area of high pressure is part of the great subtropical belt of anticyclones called the [[subtropical ridge]]. A [[cloud hole]] with an expansion as far as 1,000 kilometers (620 miles) has been observed, with tops of 1,040 [[millibar]]s. The high may be extensive enough to interconnect with the Tasman High over in the [[Tasman Sea]], just near [[New Zealand]].<ref>[https://www.farmonlineweather.com.au/news/high-pressure-systems-everything-you-need-to-know/527959#:~:text=High%20pressure%20systems%20are%20a,weather%20across%20an%20entire%20continent. High pressure systems: everything you need to know] by Ben Domensino from Weatherzone. 21 May 2018. Retrieved 22 April 2022.</ref>
==Effects==
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