
A typical summer situation is when a large high in the Great Australian Bight forms, which directs hot and gusty easterly winds from inland Australia to Perth, and a trough starts to develop down the west coast, temperatures are usually in the 30's and only a late weak sea breeze may arise.
During the next 24 hours the trough of low pressure down the west coast starts to deepen, winds become more to the north-east and the mornings are hot, with usually an earlier sea breeze bringing some relief.
The position of the trough is usually the deciding factor in how hot it gets and what time the sea breeze reaches the city. It can mean the difference of a 40 C day or a much cooler day of 25 C to 30 C.
However, the trough can also be responsible in giving much needed rain to Perth. Sometimes it can become active and produce thunderstorms particularly to the north and east of Perth, and on rare occasions bring storms to Perth it self.
Some of Perth's hottest days on record occurred back in 1991. The heat on this occasion began on the 29th January, 1991, and the maximum temperature reached 40.1 C, the next day was the first day of school for the new year, and students had to cope in extreme heat when the top hit 43.2 C. Weather forecasters expected that the trough would move inland sometime during the next 24 hours, and predicted at maximum of 39 C for the next day, however it got much hotter. That day was the 31st January, 1991, Perth sizzled overnight with a minimum of 25.5 C recorded at 5.55am, then the temperature began to climb, by 9am it was already 38 C, at 11am it was 42 C, at 1pm it was 44 C, and the new all time record was 45.8 C at 1.50pm, the sea breeze then came in and gave some small relief.
The 45.8 C record defeated the old record of 44.7 C which occurred on the 12th January, 1978, however only a few weeks later record heat was back.
It was the 23rd February, 1991, a large high pressure system was situated in the eastern half of the Great Australian Bight, and Tropical Cyclone Daphne was situated to the north of the state, between the two, very hot and strong north-easterly winds were present. Perth's minimum temperature was 25.2 C at 1am, at 7am it was 28.1 C, by 9am it was 35.3 C, at midday it was already 43.2 C and then the all time new record was established at 1.50pm with a top of 46.2 C, which beat the old record of 45.8 C some few weeks earlier.
February, 1996 will be remembered as another hot period by Perth residents, when the heat wave record of 16 days in a row of temperatures over 32 C was established, with a number of days during that period getting over the 38 C mark.
Even though Perth is known as a dry city during the summer, it can still have extreme rainfalls on a particular day if a thunderstorm or an ex-tropical cyclone hits the city.
Some notable days was the 54.6 mm on the 21st January, 1982, the 50.5 mm on the 16th February, 1955, the 87.1 mm on the 17th February, 1955, the 64.8 mm on the 22nd February, 1986 and the all time Perth record occurred in summer when 120.6 mm was dumped on the city on the 8th February, 1992. However extreme rainfall such as these during Perth summers are very rare.
Averages and extremes in Perth for the summer months:
DEC JAN FEB
Av.MAX 27.4 30.0 30.5
Av.MIN 16.5 18.3 18.7
Hi.MAX 42.3 45.8 46.2
Hi.MIN 27.1 27.8 29.3
Lo.MAX 14.9 19.6 19.0
Lo.MIN 8.6 9.2 8.7
Av.RAIN 14.0 8.0 12.0
Days when the maximum temperature in Perth City reached 35 C or above:
Summer 1996/97
20th Oct, 1996 36.9 C 11th Nov, 1996 35.9 C 19th Dec, 1996 37.4 C 31st Dec, 1996 38.6 C 1st Jan, 1997 42.2 C 2nd Jan, 1997 40.8 C 3rd Jan, 1997 39.0 C 7th Jan, 1997 37.2 C 8th Jan, 1997 40.9 C 16th Jan, 1997 37.7 C 17th Jan, 1997 37.7 C 24th Jan, 1997 38.5 C 28th Jan, 1997 39.1 C 1st Feb, 1997 42.7 C 2nd Feb, 1997 36.2 C 3rd Feb, 1997 35.0 C 25th Feb, 1997 35.7 C 26th Feb, 1997 44.5 C 27th Feb, 1997 36.7 C 15th Mar, 1997 35.3 C
The 44.5 C maximum temperature on the 26th February, 1997, was Perth's 5th hottest day on record, click here for a summary of that day.
Summer 1997/98
3rd Nov, 1997 37.5 C 9th Dec, 1997 36.8 C 10th Dec, 1997 38.9 C 15th Dec, 1997 36.3 C 22nd Dec, 1997 39.4 C 23rd Dec, 1997 41.4 C 26th Dec, 1997 40.5 C 5th Jan, 1998 38.4 C 6th Jan, 1998 41.5 C 7th Jan, 1998 42.6 C 10th Jan, 1998 35.1 C 25th Jan, 1998 38.5 C 26th Jan, 1998 39.8 C 27th Jan, 1998 36.0 C 8th Feb, 1998 35.9 C 9th Feb, 1998 40.2 C 12th Feb, 1998 35.8 C 13th Feb, 1998 36.8 C 28th Feb, 1998 41.1 C 1st Mar, 1998 37.8 C 5th Mar, 1998 37.6 C 6th Mar, 1998 39.5 C 17th Mar, 1998 35.9 C 18th Mar, 1998 35.6 C
Summer 1998/99
11th Nov, 1998 37.7 C 21st Nov, 1998 35.7 C 4th Dec, 1998 35.1 C 13th Dec, 1998 35.6 C 14th Dec, 1998 39.7 C 30th Dec, 1998 38.5 C 8th Jan, 1999 36.7 C 16th Jan, 1999 36.4 C 20th Jan, 1999 39.0 C 24th Jan, 1999 37.2 C 25th Jan, 1999 35.1 C 26th Jan, 1999 38.3 C 6th Feb, 1999 35.3 C 7th Feb, 1999 38.1 C 8th Feb, 1999 38.8 C 12th Feb, 1999 35.5 C 18th Feb, 1999 35.6 C 23rd Feb, 1999 35.2 C 24th Feb, 1999 37.1 C 25th Feb, 1999 38.1 C 26th Feb, 1999 38.0 C 27th Feb, 1999 37.6 C
Summer 1999/2000
24th Nov, 1999 36.7 C 4th Dec, 1999 38.5 C 12th Dec, 1999 35.8 C 21st Dec, 1999 36.0 C 22nd Dec, 1999 39.6 C 24th Dec, 1999 37.6 C 26th Dec, 1999 35.9 C 27th Dec, 1999 39.3 C 28th Dec, 1999 35.2 C 31st Dec, 1999 35.4 C 1st Jan, 2000 36.6 C 2nd Jan, 2000 36.5 C 3rd Jan, 2000 35.9 C 4th Jan, 2000 37.2 C 5th Jan, 2000 36.9 C 6th Jan, 2000 35.1 C 29th Jan, 2000 36.6 C 30th Jan, 2000 36.6 C 6th Feb, 2000 35.8 C 7th Feb, 2000 37.2 C 8th Feb, 2000 40.1 C 15th Feb, 2000 35.1 C 16th Feb, 2000 35.0 C 17th Feb, 2000 36.3 C 29th Feb, 2000 35.1 C 6th Mar, 2000 35.0 C 7th Mar, 2000 36.9 C 8th Mar, 2000 38.1 C 9th Mar, 2000 35.8 C
Summer 2000/01
15th Nov, 2000 37.3 C 15th Dec, 2000 35.6 C 25th Dec, 2000 37.6 C 26th Dec, 2000 38.3 C 27th Dec, 2000 40.3 C 5th Jan, 2001 35.2 C 8th Jan, 2001 36.7 C 29th Jan, 2001 35.7 C 30th Jan, 2001 35.3 C 5th Feb, 2001 36.4 C 2nd Mar, 2001 38.7 C 3rd Mar, 2001 39.7 C 4th Mar, 2001 38.9 C 5th Mar, 2001 37.7 C 6th Mar, 2001 38.5 C 4th Apr, 2001 36.2 C
Summer 2001/02
13th Nov, 2001 36.0 C 27th Nov, 2001 35.0 C 14th Jan, 2002 36.4 C 15th Jan, 2002 35.0 C 16th Jan, 2002 35.9 C 22nd Jan, 2002 35.4 C 28th Jan, 2002 36.6 C 30th Jan, 2002 35.3 C 31st Jan, 2002 36.3 C 6th Feb, 2002 37.1 C 10th Feb, 2002 35.3 C 11th Feb, 2002 35.4 C 23rd Feb, 2002 35.7 C 24th Feb, 2002 37.4 C 8th Mar, 2002 36.1 C 12th Mar, 2002 36.4 C 14th Mar, 2002 35.0 C 29th Mar, 2002 35.1 C
Summer 2002/03
14th Nov, 2002 37.9 C 11th Dec, 2002 39.3 C 12th Dec, 2002 38.6 C 18th Dec, 2002 35.6 C 19th Dec, 2002 40.2 C 20th Dec, 2002 40.7 C 22nd Dec, 2002 37.7 C 23rd Dec, 2002 37.2 C 2nd Jan, 2003 36.4 C 3rd Jan, 2003 38.1 C 8th Jan, 2003 35.4 C 9th Jan, 2003 37.9 C 10th Jan, 2003 36.5 C 15th Jan, 2003 35.7 C 16th Jan, 2003 35.0 C 21st Jan, 2003 36.6 C 27th Jan, 2003 36.6 C 1st Feb, 2003 35.6 C 7th Feb, 2003 36.2 C 8th Feb, 2003 39.7 C 9th Feb, 2003 41.0 C 7th Mar, 2003 38.1 C 8th Mar, 2003 40.0 C 9th Mar, 2003 40.8 C 10th Mar, 2003 42.0 C
Summer 2003/04
7th Nov, 2003 35.6 C 11th Nov, 2003 40.3 C 12th Nov, 2003 36.2 C 22nd Dec, 2003 37.3 C 26th Dec, 2003 38.8 C 27th Dec, 2003 36.5 C 4th Jan, 2004 35.4 C 10th Jan, 2004 37.7 C 11th Jan, 2004 40.5 C 17th Jan, 2004 35.8 C 2nd Feb, 2004 36.2 C 3rd Feb, 2004 40.6 C 12th Feb, 2004 36.5 C 15th Feb, 2004 36.2 C 16th Feb, 2004 38.5 C 17th Feb, 2004 41.5 C 18th Feb, 2004 39.5 C 24th Feb, 2004 36.0 C 29th Feb, 2004 38.6 C 21st Mar, 2004 40.0 C 22nd Mar, 2004 41.4 C 26th Mar, 2004 37.5 C
**Note: Some of these temperatures may be incorrect.