Monday 3 November, 2008

Monthly Climate Summary for Perth - Product Code: IDCKGC11LO

A warmer than normal October in Perth

October Rainfall - near average: The city received 38.4 mm of rainfall over 9 days in October compared with the average of 53 mm on about 9 days. The wettest day in October 2008 was the 25th when 20.4 mm was recorded, which was Perth's wettest October day for 5 years. Historically, October rainfall has ranged from 1.0 mm in 1969, to 199.9 mm in 1890. Last October Perth recorded 42.4 mm on 8 days.

Year to date rainfall - below average: The total rainfall for January to October this year was 738.4 mm on 97 days. The average is 820 mm on about 101 days. The total for the same period last year was 679.8 mm on 107 days.

Mean daily maximum temperature - above average: Perth's mean daily maximum temperature in October was 24.0°C, compared with the average of 22.8°C. Daily maxima ranged from a mild 18.4°C on the 2nd to a hot 35.7°C on the 20th, which was the highest daily maximum for October since the 36.9°C on 20 October 1996. 

Highest consecutive hot days on record:  During the month, Perth recorded three consecutive hot days when the maximum temperature was 32°C or higher. This is the greatest number of consecutive days over 32°C for October on record. The daily maximum temperatures were; Sunday 19th (33.5°C), Monday 20th (35.7°C) and Tuesday 21st (32.7°C). Perth also equalled its greatest total number of October days over 32°C with four, as 32.1°C was recorded on the 15th.  The only other year in which 4 days over 32°C have been recorded in October was 1969.

Mean daily minimum temperature - above average: Perth's mean daily minimum temperature in October was 12.1°C, compared with the average of 11.1°C. The lowest daily minimum temperature for the month was 3.4°C on the 5th, which was the lowest for October since the 2.5°C on 10 October 2005 and the third lowest on record for October. Perth's lowest daily minimum temperature on record was 2.2°C on 6 October 1994.

The highest daily minimum temperature for the month was a warm 21.3°C on the 20th, which was the equal second highest daily minimum temperature with the 21.3°C on 13 October 1991. Perth's highest daily minimum temperature on record was 22.2°C on 29 October 1979.

Climate of Perth in November

November days in Perth are generally sunny and either mild or warm. A few hot days occur, usually in the latter part of the month. The general springtime decline in rainfall continues with an average of 22 mm over about six days.

** Denotes the highest daily maximum temperature recorded on 24 November 1913 and 11 November 2003.

Hot days in November: On average, Perth can expect four November days when the maximum temperature is 32°C or higher. The record of nine such days was set in 1940 whilst last November Perth recorded seven such days.

Earliest 40°C day of the season: The earliest 40°C maximum temperature of the season occurred on 11 November 2003, when 40.3°C was recorded. A maximum temperature of 40°C or higher has only occurred three times in November in Perth since records began in 1897.

Note: Official Perth observations have been recorded at several different sites with varying instrumentation over the years, and these changes can affect the continuity of the climate record. For the current Mount Lawley site, the most significant changes of this kind relate to temperature and rain days. For that reason, current mean temperature and rain-day data quoted here are based only on readings from the Mount Lawley site, which commenced observations in 1993. Sunshine recordings are from Perth Airport and for similar reasons current means use only Perth Airport data, which commenced in 1993.

Further information:
John Relf (JR) and Merv Blackwell Western Australia Climate Services Centre
on, tel: (08) 9263 2222, office hours.