Climate of Perth

Perth receives moderate though highly seasonal, winter based rainfall. Summers are generally hot and dry, lasting from December to March, with February generally being the hottest month of the year. Winters are cool and wet, giving Perth a hot-summer Mediterranean climate (Köppen climate classification Csa).[1][2] Perth has an average of 8.8 hours of sunshine per day, which equates to around 3200 hours of annual sunshine, and 138.7 clear days annually, making it the sunniest capital city in Australia.[3]

Summers are dry but not completely devoid of rain, with sporadic rainfall in the form of short-lived thunderstorms, cold fronts and on occasions decaying tropical cyclones from Western Australia's north-west, which can bring heavy rain. Winters see significant rainfall as frontal systems move across the region, interspersed with clear and sunny days. The highest temperature recorded in Perth was 46.2 °C (115.2 °F) on 23 February 1991, although Perth Airport recorded 46.7 °C (116.1 °F) on the same day.[3][4] On most summer afternoons a sea breeze, known locally as the "Fremantle Doctor", blows from the southwest, providing relief from the hot north-easterly winds. Temperatures often fall below 30 °C (86 °F) a few hours after the arrival of the wind change.[5] In the summer, the 3 pm dewpoint averages at around 12 °C (54 °F).[3]

Winters are wet but mild, with most of Perth's annual rainfall being between May and September. The lowest temperature recorded in Perth was −0.7 °C (30.7 °F) on 17 June 2006.[4] The lowest temperature within the Perth metropolitan area was −3.4 °C (25.9 °F) on the same day at Jandakot Airport. However, temperatures at or below zero are very rare occurrences. It occasionally gets cold enough for frost to form.[6] While snow has never been recorded in the Perth CBD, light snowfalls have been reported in outer suburbs of Perth in the Perth Hills around Kalamunda, Roleystone and Mundaring. The most recent snowfall was in 1968.

Rain

The rainfall pattern has changed in Perth and southwest Western Australia since the mid-1970s. A significant reduction in winter rainfall has been observed with a greater number of extreme rainfall events in the summer months,[7] such as the slow-moving storms on 8 February 1992 that brought 120.6 millimetres (4.75 in) of rain,[4][5] heavy rainfall associated with a tropical low on 10 February 2017, which brought 114.4 millimetres (4.50 in) of rain,[8] and the remnants of ex-Tropical Cyclone Joyce on 15 January 2018 with 96.2 millimetres (3.79 in).[9] Perth was also impacted by a severe thunderstorm on 22 March 2010, which brought 40.2 mm (1.58 in) of rain and large hail and caused significant damage in the metropolitan area.[10]

Temperatures

The average temperature of the sea ranges from 18.9 °C (66.0 °F) in October to 23.4 °C (74.1 °F) in March.[11]

Climate data for Perth, Western Australia
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Record high °C (°F) 45.8
(114.4)
46.2
(115.2)
42.4
(108.3)
37.6
(99.7)
34.3
(93.7)
28.1
(82.6)
26.3
(79.3)
30.0
(86.0)
34.2
(93.6)
37.3
(99.1)
40.4
(104.7)
44.2
(111.6)
46.2
(115.2)
Mean maximum °C (°F) 40.4
(104.7)
40.1
(104.2)
38.6
(101.5)
33.7
(92.7)
28.8
(83.8)
24.1
(75.4)
22.7
(72.9)
24.3
(75.7)
27.1
(80.8)
32.9
(91.2)
36.7
(98.1)
39.4
(102.9)
41.8
(107.2)
Average high °C (°F) 31.2
(88.2)
31.6
(88.9)
29.6
(85.3)
25.9
(78.6)
22.3
(72.1)
19.5
(67.1)
18.4
(65.1)
19.1
(66.4)
20.4
(68.7)
23.4
(74.1)
26.7
(80.1)
29.1
(84.4)
24.8
(76.6)
Average low °C (°F) 18.1
(64.6)
18.3
(64.9)
16.7
(62.1)
13.8
(56.8)
10.5
(50.9)
8.6
(47.5)
7.9
(46.2)
8.3
(46.9)
9.5
(49.1)
11.6
(52.9)
14.3
(57.7)
16.3
(61.3)
12.8
(55.1)
Mean minimum °C (°F) 12.7
(54.9)
13.0
(55.4)
10.0
(50.0)
7.6
(45.7)
4.4
(39.9)
2.3
(36.1)
1.7
(35.1)
2.6
(36.7)
3.6
(38.5)
5.4
(41.7)
8.8
(47.8)
11.0
(51.8)
1.1
(34.0)
Record low °C (°F) 8.9
(48.0)
8.7
(47.7)
6.3
(43.3)
4.1
(39.4)
1.3
(34.3)
−0.7
(30.7)
0.0
(32.0)
1.3
(34.3)
1.0
(33.8)
2.2
(36.0)
5.0
(41.0)
7.9
(46.2)
−0.7
(30.7)
Average rainfall mm (inches) 20.2
(0.80)
13.1
(0.52)
19.7
(0.78)
35.7
(1.41)
89.4
(3.52)
124.5
(4.90)
145.9
(5.74)
126.0
(4.96)
84.8
(3.34)
38.8
(1.53)
21.8
(0.86)
10.9
(0.43)
733.2
(28.87)
Average precipitation days 2.9 2.2 4.5 6.8 11.3 14.3 17.3 16.0 14.9 9.2 5.6 3.5 108.5
Average afternoon relative humidity (%) (at 15:00) 39 38 40 46 50 56 57 54 53 47 44 41 47
Mean daily sunshine hours 11.5 11.0 9.6 8.3 6.9 5.9 6.1 7.2 7.7 9.6 10.6 11.5 8.8
Source: Bureau of Meteorology[12][13][14]
Temperatures: 1993–2019; Extremes: 1897–2019; Rain data: 1993–2018

Daylight

Climate data for Perth
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Mean daily daylight hours 14.0 13.0 12.0 11.0 10.0 10.0 10.0 11.0 12.0 13.0 14.0 14.0 12.0
Source: Bureau of Meteorology (daylight hours)[17]

UV Index

Climate data for Perth
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Average ultraviolet index 12 11 9 6 4 2 3 4 6 8 10 12 7.2
Source: Bureau of Meteorology (UV index)[18]

Sea temperature

Climate data for Perth
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Average sea temperature °C (°F) 21.0
(69.8)
21.6
(70.9)
21.8
(71.2)
21.3
(70.3)
21.1
(70.0)
20.3
(68.5)
20.1
(68.2)
19.2
(66.6)
18.7
(65.7)
19.1
(66.4)
20.3
(68.5)
20.1
(68.2)
20.4
(68.7)
Source: METOC (sea temperature),[19]

See also

References

  1. Tapper, Andrew; Tapper, Nigel (1996). Gray, Kathleen (ed.). The weather and climate of Australia and New Zealand (First ed.). Melbourne, Australia: Oxford University Press. p. 300. ISBN 0-19-553393-3.
  2. Linacre, Edward; Geerts, Bart (1997). Climates and Weather Explained. London: Routledge. p. 379. ISBN 0-415-12519-7.
  3. "Perth Airport climate statistics". Bureau of Meteorology. Retrieved 25 December 2012.
  4. "Annual Climate Summary for Perth: Near average rainfall with warmer days for Perth in 2008". Bureau of Meteorology. 2 January 2009. Retrieved 5 August 2009.
  5. Courtney, Joe; Middelmann, Miriam (2005). "Meteorological hazards" (PDF). Natural hazard risk in Perth, Western Australia – Cities Project Perth Report. Geoscience Australia. Retrieved 25 December 2012.
  6. "Jandakot Airport climate statistics". Bureau of Meteorology. Retrieved 2 September 2015.
  7. "How extreme south-west rainfalls have changed". Indian Ocean Climate Initiative. 2000. Archived from the original (PDF) on 23 July 2009. Retrieved 5 August 2009.
  8. "Perth, Western Australia February 2017 Daily Weather Observations". Bureau of Meteorology. Retrieved 10 February 2017.
  9. "Perth, Western Australia January 2018 Daily Weather Observations". Bureau of Meteorology. Retrieved 19 January 2018..
  10. O'Connell, Ronan; McPhee, Lindsay; Hiatt, Bethany (23 March 2010). "Storm brings huge damage bill". The West Australian. Archived from the original on 3 December 2011. Retrieved 23 March 2010.
  11. Copyright Global Sea Temperatures — A-Connect Ltd. "Perth Sea Temperature | Australia Water Temperatures". 31.952240;115.861400: Seatemperature.org. Retrieved 2017-09-23.CS1 maint: location (link)
  12. "Climate statistics for Australian locations". Bureau of Meteorology. Retrieved 2 November 2019.
  13. "Monthly highest temperature". Bureau of Meteorology. Retrieved 22 January 2019.
  14. "Monthly lowest temperature". Bureau of Meteorology. Retrieved 22 January 2019.
  15. "Climate Statistics for Fremantle, WA". Retrieved 16 May 2012.
  16. "Climate statistics for Kalamunda". Bureau of Meteorology. Retrieved 21 June 2011.
  17. "Perth, Australia — Perth Metro Climatic Averages" (PDF). Bureau of Meteorology. Retrieved 17 March 2017.
  18. "Average solar ultraviolet (UV) Index". Bureau of Meteorology. Retrieved 19 April 2020.
  19. "Perth, Australia — Coastal Sea Surface Temperatures". Metoc. Archived from the original on 6 July 2007. Retrieved 17 March 2017.
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