Climate of Sydney

The climate of Sydney, Australia is humid subtropical, shifting from mild and cool in winter to warm and occasionally hot in the summer, with no extreme seasonal differences since the weather has some maritime influence. Contrasting temperatures are recorded in the western suburbs, as Sydney CBD is more affected by the oceanic climate drivers than the hinterland. Despite the fact that there is no distinct dry or wet season, rainfall peaks during summer and autumn months, and is at its lowest just around the middle of the year, though precipitation can be erratic throughout the year. Precipitation varies across the region, with areas adjacent to the coast being the wettest.
In the February 1938 issue of The Home, journalist Basil Burdett wrote, "...Even Melbourne seems like some grey and stately city of Northern Europe compared with Sydney's sub-tropical splendours." In 2023, Sydney was placed at 9th place by Stars Insider for having the best weather in the world. Though in 1788, Lieutenant Ralph Clark, a member of the First Fleet, stated that the thunderstorms were the most terrible he has ever experienced. In 1819, Australian explorer William Wentworth described the summer heat as "sometimes excessive" and "oppressive to Europeans", although he noted that sea breezes effectively moderated temperatures.

General climatology

According to the Bureau of Meteorology, Sydney falls in the temperate climate zone with warm to hot summers and no dry season. Under the Holdridge Life Zones classification, coastal Sydney falls in the Subtropical Moist Forest zone and the inland, western suburbs in the Subtropical Dry Forest zone. According to Troll-Paffen climate classification, Sydney has a warm-temperate subtropical climate. Sydney's plant hardiness zone ranges from zone 11a in the east to 9b in the far west.
Sydney has 109.5 clear days and 127.2 cloudy days annually, though it has around 200 days of visible sunshine if partly cloudy days or sunny breaks are counted. Overall, Sydney has just about 66% of possible sun for Jun-Aug and around 54% for Dec-Feb, making winter sunnier than summer on average, in addition to the city being sunny around 65% of the time in the year with its 2,640 hours of annual sunshine. On some hot summer days, southerly busters decrease temperatures by late afternoon or early evening. In the warm season, troughs combined with a humid air mass can bring large amounts of rainfall. In late autumn to early winter, the city can be affected by east coast lows. Afternoon windspeed recorded in Sydney Airport averages at 24.3 km/h in an annual basis, making Sydney the windiest capital city in Australia.
Sydney experiences an urban heat island effect, making certain parts of the city more vulnerable to extreme heat, particularly the west. Efforts have been introduced to investigate and mitigate this heat effect, including increasing shade from tree canopies, adding rooftop gardens to high rise structures and changing pavement colour. The El Niño Southern Oscillation, the Indian Ocean Dipole and the Southern Annular Mode play an important role in determining Sydney's weather patterns: drought and bushfire on the one hand, and storms and flooding on the other. Sydney is prone to heat waves and drought, which have become more common in the 21st century.
The region of Sydney, and as well as the rest of the New South Wales coastline, is warmed by the East Australian Current. In 2020, researchers at The Australia Institute discovered that Sydney was experiencing longer summers and shorter winters in recent decades, compared to those in the 1950s and 1960s. Since the early 1990s, Western Sydney has experienced more intense summer heatwaves than coastal Sydney, with maximum temperatures exceeding those of coastal Sydney by up to. Moreover, since the early 2020s, Sydney's summers have become more humid due to global warming, which result in sea temperatures being above normal.

Seasons

Summer

Summer is generally warm to hot, and often humid. The ultraviolet index rating averages at 12, but can reach 13 in the midst of the season, which may lead to skin damage among those having light skin.
Sydney can receive hot, dry northwesterly winds from the Outback that make the temperatures soar above. This happens after the northwesterlies are carried entirely over the continental landmass, not picking up additional moisture from a body of water and retaining most of their heat. On these occasions, the city can experience the fury of the desert climate, although they are often ended with a southerly buster, which is a windy, shallow cold front or a sea breeze that sweeps up from the southeast abruptly cooling the temperature. At times, it may be accompanied by a thunderstorm and drizzle, and it may keep the temperatures cool the following few days as well.
In the Sydney central business district, an average of 15 days a year have temperatures of more than and 3 days with temperatures over. In contrast, western suburbs such as Liverpool and Penrith have 41 and 67 days with temperatures above, 10 and 19 days above, and, 1 and 4 days above, respectively.
The highest recorded maximum temperature at Sydney Airport was 46.4 °C, which was on 18 January 2013. The highest recorded maximum temperature at Sydney CBD was recorded on that same day with the temperature climaxing at 45.8 °C. The highest recorded maximum temperature within Sydney's Metropolitan area was recorded at Penrith with a high of 48.9 °C, a Western Sydney suburb, on 4 January 2020. At that time, Penrith was the hottest place on the planet and the hottest temperature recorded within Australia and the Southern Hemisphere for all of 2020.

Autumn

Late summer conditions usually continue until the last week of March. Most heavy rainfall events usually occur in late summer and early autumn as the subtropical ridge of high pressure, which rotates counterclockwise, is to the south of Australia and therefore give way for moist easterlies from the Tasman Sea and as well as low pressure systems to penetrate the region.
The transition from late summer to autumn is gradual, with noticeably cooler and crisper conditions taking in effect by around mid-April. Temperatures in autumn are usually consistent and stable, lacking any extremes that tend to be experienced in spring and summer.
The lowest maximum temperature in autumn is, recorded on 24 May 1904. The highest maximum autumn temperature ever recorded at Sydney Airport was recorded on 9 March 1983, with the temperature peaking at. Though the hottest autumn day ever recorded in Sydney's metropolitan area was on 6 March 1938 when Richmond RAAF hit.

Winter

Winter in central Sydney tends to be mild where the lows rarely drop below, mainly due to proximity to the ocean. Furthermore, Sydney CBD has never recorded frost. In the far west, the diurnal range can be relatively great, particularly in late winter. In the west, Liverpool and Richmond have 4 and 38 nights, respectively, where temperatures dip below. On average, only 1 night in Liverpool and 17 nights in Richmond have lows that go below. In such cold mornings, frost can form in the far western suburbs. The lowest maximum temperature in Liverpool was, recorded on 28 July 1981.
Sydney receives around 15 days of fog annually, which occurs in winter mornings; some can be thick enough to divert planes and cancel ferry services. During late winter, warm dry westerly winds which dominate may raise the maximum temperatures as high as in some instances. As the subtropical ridge is north of Sydney in mid-to-late winter, it picks up dry westerlies from the continent's interior because of its anticlockwise rotation, thus producing more sunny days in the region.
The lowest recorded minimum at Observatory Hill was on 22 June 1932, while the coldest in the Sydney metropolitan area was, in Richmond. The lowest recorded maximum temperature at Observatory Hill was. Although not usually considered a suburb of Sydney, Picton, a town in the Macarthur Region of Sydney, recorded a low of on 16 July 1970.
Sydney's warmest winter day was recorded on 30 August 2024 at Sydney Airport when the temperature hit at 2:48 PM.

Spring

Early spring is rapidly transitional and erratic. Cool conditions from late winter may continue in September, but due to the drastic transition, temperatures above can also be expected in that month, including the odd thunderstorm. By November, summery conditions begin, albeit with relatively low humidity. Because the subtropical ridge lies to the north of Sydney this time of the year, it will bring westerly winds from the interior that produce mostly sunny conditions, with relatively low dewpoints. Extreme, changeable and inconsistent temperatures are much more prevalent in spring than other seasons. Furthermore, the diurnal range is higher in this season than it is in autumn.
The lowest maximum temperature in spring was, recorded on 8 September 1869. 9am relative humidity is the lowest in the year during spring, ranging from 58% to 68%, with early spring receiving lower figures. The highest maximum Spring temperature ever recorded at Sydney Airport was on 25 November 1982, when the temperature eclipsed at. Sydney CBD also recorded its hottest spring day on this same day, peaking at. The highest spring temperature recorded in Sydney's Metropolitan area was registered at Richmond on 23 November 2014, peaking at.

Warm and cool periods

The Bureau of Meteorology reported in 2011 that 2002 to 2005 had been the warmest years in Sydney since records began in 1859. The year 2004 saw an average daily maximum temperature of, 2005 of, 2002 of, and 2003 of. The average daily maximum between 1859 and 2004 was. Seven warmest years in 151 years of recordkeeping have occurred in the ten years between 2001 and 2010, with this decade being the warmest on record for minimum temperatures.
The Bureau of Meteorology reported that the summer of 2007–08 was the coolest in 11 years, the wettest in six years, the cloudiest in 16 years, and one of only three summers in recorded history to lack a maximum temperature above. The Bureau of Meteorology reported that 2009 was a warm year. The average annual daytime temperature at Observatory Hill was, which is above the historical annual average. This ranks as the seventh highest annual average maximum temperature since records commenced in 1859. The year 2010 was the equal fourth warmest year on record for Sydney, with an average maximum of, which was above the historical annual average.
Climate models in 2014 suggested that sea temperatures off Sydney are decades away from becoming "tropical". A scenario of increasing CO₂ emissions proposed winter sea surface temperatures will consistently exceed between 2020 and 2030, and summer sea surface temperatures will consistently surpass between 2040 and 2060.
July 2017 to June 2018 in southeastern Australia proved to be the hottest financial year on record with maximum temperatures being the warmest on record and minimums above average. The warmest year on record was 2016, with a mean temperature of degrees. Sydney's 2017 mean temperature of degrees was degrees above the long term average and the second highest value in 158 years of records. The 2020-21 summer was the coolest in a decade due to La Nina's influence.

Microclimate

The region of Sydney is subject to phenomena typical of a microclimate, namely in late spring and summer, where the western suburbs are hotter than the Sydney CBD by due to urban sprawl exacerbating the urban heat island effect and less exposure to mitigating sea breezes which cool down Sydney's eastern edge and fail to move inland. The dramatic temperature difference between coastal and inland areas is caused by a combination of desert-warmed air from central Australia reaching the west, and as well as density of housing, lack of vegetation or open spaces, and the Blue Mountains which help trap the hot air.
When it is at Bondi for instance, the temperature will be around just west of the Sydney Harbour Bridge, around near Parramatta and as much as inland. Such extreme temperature differences in the Sydney metropolitan area usually occur in late spring when the western Pacific Ocean is still quite cool and the inland air is warm. Furthermore, within the CBD, heat maps show the area around Central Station is warmer than Circular Quay and surrounds, making it the hottest place in the CBD.
According to ecologist Sebastian Pfautsch from the University of Freiburg, in Sydney's hot days there could be discrepancies of up to 22 more days above recorded in urban space compared to a weather station from the Bureau of Meteorology. Because was recorded in Penrith, it will not be unusual to have a reading somewhere nearby, especially if it lacked green space and retained heat to intensify heatwave temperatures.
Richmond has the second largest overall temperature range recorded in Australia, after Mitchell, Queensland;.

Urban heat island

A study by the University of Western Australia and RMIT indicated that the western suburbs have a much stronger urban heat island effect than those east of the CBD and that hotter temperatures in the west are human contributed due to solar radiation absorbing materials in black asphalt and dark roofs, anthropogenic heat from cars and less natural environments, thereby creating a "heat dome" that blocks the cooler air from the sea. Greening Australia stated that January mean maximum temperatures in the west have risen at a pace of 0.65 °C per decade, over twice as much as eastern Sydney's 0.28 °C per decade. The OEH warned that further development could cause more exceedingly hot days in the west by 2030.
Urban heat island of the CBD has been efficaciously blocking the cooler air from reaching the inland suburbs because the CBD's "high temperature, is like a wall that stops the sea breeze in its tracks. Over Sydney’s CBD is a heat dome because of the high density of concrete and asphalt. If we want to cool western Sydney and demolish this wall, we need to cool the CBD first", Professor Mattheos Santamouris from UNSW states. He explained that cooling the CBD would reduce the temperature by 1.5 °C in the west and tree coverage could cool down suburban streets by as much as 10 °C in hot days since high-density housing developments and scarce trees trap heat. Waterbodies and open spaces also provide cooling benefits in urban areas.
According to climate researchers, relatively easy modifications such as constructing fountains and water playgrounds could also lower temperatures in the western suburbs. The city now has 3.6% more trees in 2016 than it did in 2009 and Penrith City Council had planned to plant 100,000 trees from August 2018, in addition to planning a large city park, creating a water-sensitive urban design, street shading, and the use of cool materials in its building developments. Furthermore, Parramatta City Council has installed 20 temperature sensors among different tree species in its suburbs to compare how different species can help reduce urban heat.

Precipitation

Rainfall is slightly higher or dominant during the first half of the year, particularly in late summer and early autumn, when the ocean has peaked its warmth. Rainfall will tend to be lower in the second half of the year when the subtropical ridge is just to the north of the city. Most rain comes mostly from major storms, rarely drizzle, particularly from subtropical lows that bring warm, moist air onshore.
Due to the unpredictability of rain, the wettest and driest months change on a yearly basis. Rain falls on 40% of days, anytime of the year, but usually in January to June. Coastal showers, which are a mix of convective and stratiform, occur in post-frontal south-east flow, where they become volatile over the warm ocean near Sydney, thereby setting up an "ocean-effect".
Frontal lows frequently affect Sydney in winter, but they are generally dry because such lows remain farther south, and the cold front's passage is connected with a shift from warm and dry northwesterly winds to colder, damp south-westerlies, which lose much of their moisture over the Great Dividing Range. Therefore, the drier winters are due to its rain shadow position on the leeward side of the Great Dividing Range, which shield the region from south-westerly cold fronts that arrive from the Southern Ocean.
Within the city and surrounds, rainfall varies, from around at Badgerys Creek to at Turramurra in the Northern Suburbs, which create an orographic rainfall. The annual evaporation rate for Sydney is, with the rate in the summer being and in winter.

Storms

East coast lows, which strike from the southeast in the Tasman Sea, bring heavy rainfall typically in autumn to early winter. The precipitation of the low comes from a nimbostratus cloud that dumps as much as of rain for as much as two days. Sydney generally experiences between 20 and 25 thunder days a year on average. Thunderstorms arrive from the west, and normally involve northeasterly winds at the surface.
The western suburbs are more inclined to receive thunderstorms in summer due to the stabilizing effect of a sea breeze in the afternoon near the CBD and Eastern Suburbs. Isolated convective showers form when a cold pool arrives from the southwest, particularly on hot and sultry days. These showers usually come in heavy downpours and can include hail, squalls, and drops in temperature, but they generally pass very quickly. Black nor'easters may bring persistent rainfall for a few consecutive days in the warm months, and Australian northwest cloudbands produce light rainfall in the cool months.
The city is rarely affected by cyclones, although remnants of ex-cyclones do affect the city. The city is prone to severe hailstorms, windstorms, and flash flooding. Scientists have predicted that rainfall will become more unpredictable and temperatures will be on the rise.
In 2011, Sydney recorded its wettest July since 1950, where the CBD recorded of rain that month. The year 2011 was also the wettest year since records began in 1858. Parts of western Sydney were substantially flooded during the New South Wales 2021 floods, with many areas around Richmond and Windsor submerged in floodwaters. In early 2022, Sydney recorded its wettest start to a year on record with the running annual total being, topping to the same date in 1956 and in 1990, respectively.

Snowfall

Snow is extremely rare in Sydney, with significant snowfall being last reported in the Sydney area on 28 June 1836. On that date, it was reported that convicts and British settlers in Hyde Park woke up to snow "nearly deep", with the meteorological table in The Sydney Herald recording that on the morning of the snow the temperature dropped to. The snow event affected trading where sellers were unable to transport goods to markets in the colony. The snowfall occurred at the end of the dalton minimum, a solar cycle period representing low solar activity, where colder temperatures were recorded globally. A keeper of weather observations during that period, T. A. Browne noted:
The Sydney Morning Herald reported on the event, saying:
The Sydney Monitor reported:
Scant snowfall has been recorded in latter dates:

On 22 June 1951, light snowflakes were reported in the suburbs of Liverpool, Pymble and Kingsgrove.
On 25 July 1986, melting snow was observed in Sydney CBD, Sydney Airport and Bankstown, which did not settle on the ground.
On 27 July 2008, a fall of graupel or soft hail, blanketed Lindfield, Roseville and Killara in white. Owing to this event, a senior forecaster from the Bureau of Meteorology doubted the 1836 snow account, stating that weather observers in that time period lacked the technology and skill to distinguish snow from soft hail.

Drought

Sydney's winter rainfall is predicted to decrease by 20-35% by the year 2090. The other phenomenon that arises from these long, dry and hot periods is bushfires, which occur frequently in the areas surrounding the city. Water supply is a recurring concern for the city during drought periods.
In 2005 the reservoirs reached an all-time low. Many areas of the city bordering bushland have experienced bushfires, notably in 1994 and 2001–02 — these tend to occur during the spring and summer. Heatwaves, which are regularly occurring in recent years, usually lead to water restrictions and a high risk of bushfires, which sometimes bring a smoky haze to the city. Smog is noticeable on hot days, even without bushfires. The years 2009 and 2010 had dry conditions, according to Bureau of Meteorology.
In September 2013, the combination of dry weather, warm temperatures and strong winds brought early-season bushfires. The summer of 2013-14 was the driest in 72 years. The widespread bushfires in December 2019 affected the western periphery of the city, and the Sydney metropolitan area suffered from dangerous smoky haze for several days throughout the month 2019 was one of Sydney's warmest in 161 years and the driest since 2005, which had a few days of raised dust and as well as declining dam levels.

Wind

As a whole, the Sydney region is generally the windiest from October to January and calmest from March to June. The windier locations are those by the coast, such as the eastern suburbs. The prevailing winds are seasonal in coastal Sydney; northeasterly sea breezes arriving in the summer provide relief on hot days; in winter and early spring, generally strong and cool winds come from the west or north-west, which are related to large scale synoptic events. Summer winds from the south may be strong. Spring and autumn winds tend to be variable.
Northeasterlies and easterly sea breezes are dominant from early summer to early autumn, because the anticlockwise-rotating subtropical ridge is to the south of the city where it allows winds from the sea to penetrate. Westerlies are dominant in late winter to mid-spring as the subtropical ridge is just to the north of the city, picking up winds from the interior and blocking easterlies from the sea. Westerly winds in Sydney are intensified when the Roaring forties contract towards the southeastern Australia.
Southerly busters are expected from October to the end of March. They typically look like as if a sheet of cloud is rolled up like a scroll by the advancing wind. The change of wind is sometimes very sudden, where it may be fresh northeasterly and in ten minutes a southerly gale. Katabatic winds are light, south-westerly drainage winds, akin to land breezes, that occur when air of higher density in the Blue Mountains descends under gravity force into the Sydney metropolitan area and the Hawkesbury Basin, usually during a winter night.
Since Sydney is located on the Great Dividing Range's eastern side, and is thus in its rain shadow, it experiences a föhn-like type of wind, particularly between late autumn and early spring, which is a dry south-westerly that raises the air temperature and provides clear to partly sunny conditions in the lee of the mountains, after the arrival of a vigorous westerly cold front from the Southern Ocean. In the cool season, these föhn-like winds can be particularly damaging to homes and affect flights.

Air masses

Sydney is affected by five air mass types throughout the year:

Tropical continental : Very hot, dry air from northern half of central Australia that can bring extreme heat, typically from late spring to summer. These come from the northwest and are called north-westerlies.
Tropical maritime Tasman : Mild to warm, moist airmass from the northern Tasman Sea that brings overcast, humid, sometimes showery conditions and even heavy rain at any time of the year. These are north-easterlies or northerlies.
Subtropical continental : Mild to warm, dry air from southern central Australia that is more dominant in late winter to early spring. These are westerlies.
Southern maritime : Mild to cool, moist air from the Southern Ocean that brings drizzle and, at times, cloud cover at any time of the year. These are southerlies or south-easterlies.
Modified polar maritime : Cool, sometimes cold, generally dry airmass, typically occurring in winter, that can be very windy when it arrives from the southwest over the Great Dividing Ranges. These are south-westerlies.

Historical descriptions

Aboriginal seasons

The Sydney Basin is in the traditional lands of the Dharawal people. The Dharawal describe six seasons for their country which extends from the southern shores of Port Jackson to the northern shores of the Shoalhaven River, and from the eastern shores of the Wollondilly River system to the eastern seaboard.

January–March : Hot and dry
April–June : Wet, becoming cooler
June–July : Cold, frosty, short days
July–August : Cold and windy
September–October : Cool, getting warmer
November–December : Warm and wet

European settlers

;Winter cold
On 18 July 1791, Watkin Tench described a particularly cold morning for Sydney's standards, in the area that is now Carramar, near a waterbody that was most likely to be Prospect Creek. Tench carried a thermometer in the area to record the unusually cool temperatures, in which he stated that "a degree of cold for the latitude of the place that I think myself bound to transcribe it." Such cold mornings can be attributed to the The Little Ice Age, which extended from the 16th to the 19th centuries, and would have affected south-east Australia's climate in the late 18th century, which was at the time when Europeans first colonized Australia.
On his diary entry regarding the cold conditions, he wrote:
Notwithstanding, Tench stated that Sydney's climate at that time was still warm enough to sustain plant life all year round: "Nor will this surprise, if the genial influence of the climate be considered. Placed in a latitude where the beams of the sun in the dreariest season are sufficiently powerful for many hours of the day to dispense warmth and nutrition, the progress of vegetation never is at a stand."
;Microclimate
In December 1791, Lieutenant General Watkin Tench described the difference between the climate of Sydney CBD and inland areas such as Parramatta, which included the microclimate, the diurnal range, and as well as a record of snowflakes:
;Summer heat
In 1791–92, Tench described the summers as uncomfortably hot, where settlers felt "A temporary sickness at the stomach, accompanied with lassitude and headache". The heat was reported to be "occasioned by the wind blowing over immense deserts...in a north-west direction from Port Jackson". The heat attested in that summer was so intense that it killed bats and parrots in the area.
In 1819, British explorer William Wentworth describes Sydney's climate as being pleasant, though he focuses particularly on the summer heat:

Seasons

Below, Wentworth describes Sydney's seasonal and annual weather patterns in analytical detail: