climate change wa

ACORN 2 influence on Western Australia temperature trends


In late 2018 the Australian Bureau of Meteorology provided access to the ACORN 2 daily temperatures (Australian Climate Observations Reference Network - Surface Air Temperatures), which is the bureau's dataset of homogenised or adjusted raw temperatures at 112 Australian weather stations dating back to 1910.

It is assumed that ACORN 2 will replace the ACORN 1 dataset (introduced in 2012) as the historic reference used for comparison of modern temperatures. These are usually presented to the public as temperature anomalies compared to a 1961-90 baseline at each weather station.

There are 25 ACORN stations in Western Australia, although only 24 of the ACORN 2 sites can presently be analysed because the BoM has erroneously placed Halls Creek temperatures into the Kalumburu site file for maximum temperatures.

This website has annualised the daily temperatures in ACORN 1 and ACORN 2, and below are charts showing the difference between the two datasets. It should be noted that annualised daily temperatures are influenced by the numbers of consecutive days on which temperatures were not recorded at different sites, although an attempt has been made to delete spurious years with such errors in the charts below.

Nine WA stations begin in 1910 and end in 2017 in both ACORN 1 and ACORN 2, and the first charts show maximum and minimum temperatures trends at these stations with associated data that, although not indicative of all 25 ACORN stations across WA, suggest the new ACORN 2 dataset has warmed Western Australia's maximum by 0.21C and minimum by 0.09C during 1910-1963 vs 1964-2017 (first and second halves) when compared to the ACORN 1 homogenisation.

It appears that the predominant change in ACORN 2 compared to ACORN 1 is a significant cooling of maximum temperatures in the historic records. For example, Bridgetown's average maximum temperature in 1910 is 21.6C in ACORN 1 and 20.8C in ACORN 2, while Perth's average maximum in 1910 is 23.90C in ACORN 1 and 23.42C in ACORN 2. The first day of ACORN listings in Esperance, 3 January 1910, is 32.3C in ACORN 1 and 29.1C in ACORN 2.

Alternatively, ACORN 1 lists the daily maximum at WA's chilly south coastal town of Albany on 8 February 1933 as 51.2C, making it the hottest day ever recorded in Australia, whereas ACORN 2 adjusts this day down to 49.5C, making it Australia's equal ninth hottest ever day (Albany's raw temperature on 8 February 1933 was 44.8C). The Pilbara town of Marble Bar recorded 48.9C in ACORN 1 on 1 January 1973, but 49.8C in ACORN 2 - making it the equal fourth hottest day ever recorded in Australia, according to the BoM's temperature records, and hotter than the site's claimed all-time record of 49.3C on 27 December 2018 (Marble Bar's raw temperature on 1 January 1973 was 48.8C). ACORN 1 and ACORN 2 list Forrest's maximum as 50.1C on 13 Jan 1979, making it Australia's fourth hottest ever day (Forrest's raw temperature on 13 January 1979 was 49.8C).

acorn 2 wa maximum temperatures

1910-1963 - v1 26.69C / v2 26.35C / raw 26.71C

1964-2017 - v1 27.07C / v2 26.94C / raw 27.11C

v1 warmed 0.38C / v2 warmed 0.59C

1961-90 - v1 26.92C / v2 - 26.70C

2016-2017 - 27.29C

acorn 2 wa minimum temperatures

1910-1963 - v1 14.79C / v2 14.68C / raw 14.96C

1964-2017 - v1 15.28C / v2 15.26C / raw 15.37C

v1 warmed 0.49C / v2 warmed 0.58C

1961-90 - v1 15.08C / v2 - 15.06C

2016-2017 - 15.63C

Albany

acorn 2 albany maximum temperatures

1910-1963 - v1 20.04C / v2 19.55C / raw 19.81C

1964-2013/17 - v1 20.00C / v2 20.05C / raw 20.32C

v1 cooled 0.04C / v2 warmed 0.50C

1961-90 - v1 19.92C / v2 - 19.84C

2016-2017 - 20.32C

acorn 2 albany minimum temperatures

1910-1963 - v1 10.04C / v2 10.07C / raw 11.76C

1964-2013/17 - v1 10.52C / v2 10.62C / raw 10.57C

v1 warmed 0.48C / v2 warmed 0.55C

1961-90 - v1 10.42 / v2 - 10.58C

2016-2017 - 10.23C

Bridgetown

acorn 2 bridgetown maximum temperatures

1910-1963 - v1 22.07C / v2 21.27C / raw 22.44C

1964-2011/17 - v1 22.43C / v2 21.85C / raw 22.46C

v1 warmed 0.36C / v2 warmed 0.58C

1961-90 - v1 22.18C / v2 - 21.56C

2016-2017 - 21.75C

acorn 2 bridgetown minimum temperatures

1910-1963 - v1 7.42C / v2 7.68C / raw 7.70C

1964-2011/17 - v1 8.57C / v2 8.45C / raw 8.60C

v1 warmed 1.15C / v2 warmed 0.77C

1961-90 - v1 8.38C / v2 - 8.38C

2016-2017 - 8.41C

Broome

acorn 2 broome maximum temperatures

1910-1963 - v1 31.96C / v2 31.42C / raw 32.09C

1964-2017 - v1 32.27C / v2 32.16C / raw 32.27C

v1 warmed 0.31C / v2 warmed 0.74C

1961-90 - v1 32.19C / v2 - 32.00C

2016-2017 - 33.14C

acorn 2 broome minimum temperatures

1910-1963 - v1 21.38C / v2 21.34C / raw 21.25C

1964-2017 - v1 21.27C / v2 21.73C / raw 21.31C

v1 cooled -0.11C / v2 warmed 0.39C

1961-90 - v1 20.92C / v2 - 21.61C

2016-2017 - 22.55C

Cape Leeuwin

acorn 2 cape leeuwin maximum temperatures

1910-1963 - v1 19.23C / v2 19.31C / raw 19.52C

1964-2017 - v1 19.89C / v2 19.84C / raw 20.02C

v1 warmed 0.66C / v2 warmed 0.53C

1961-90 - v1 19.77C / v2 - 19.64C

2016-2017 - 19.83C

acorn 2 cape leeuwin minimum temperatures

1910-1963 - v1 14.27C / v2 13.69C / raw 14.00C

1964-2017 - v1 14.44C / v2 14.39C / raw 14.26C

v1 warmed 0.17C / v2 warmed 0.70C

1961-90 - v1 14.29C / v2 - 14.17C

2016-2017 - 14.32C

Carnarvon

acorn 2 carnarvon maximum temperatures

1910-1963 - v1 27.35C / v2 27.50C / CDO raw 26.71C

1964-2017 - v1 27.58C / v2 27.93C / CDO raw 27.50C

v1 warmed 0.23C / v2 warmed 0.43C

1961-90 - v1 27.42C / v2 - 27.69C

2016-2017 - 27.88C

acorn 2 carnarvon minimum temperatures

1910-1963 - v1 15.91C / v2 16.19C / CDO raw 17.16C

1964-2017 - v1 17.07C / v2 17.04C / CDO raw 17.22C

v1 warmed 1.16C / v2 warmed 0.85C

1961-90 - v1 16.86C / v2 - 16.87C

2016-2017 - 17.21C

Cunderdin

acorn 2 cunderdin maximum temperatures

1951-1983 - v1 24.72C / v2 24.54C / raw 24.96C

1984-2017 - v1 25.56C / v2 25.54C / raw 25.68C

v1 warmed 0.84C / v2 warmed 1.00C

1961-90 - v1 24.75C / v2 - 24.64C

2016-2017 - 25.53C

acorn 2 cunderdin minimum temperatures

1951-1983 - v1 10.42C / v2 10.07C / raw 11.56C

1984-2017 - v1 10.49C / v2 10.42C / raw 10.97C

v1 warmed 0.07C / v2 warmed 0.35C

1961-90 - v1 10.55C / v2 - 10.21C

2016-2017 - 10.25C

Dalwallinu

acorn 2 dalwallinu maximum temperatures

1957-1978/86 - v1 25.78C / v2 25.54C / raw (1957-87) 25.83C

1979/87-2011/17 - v1 26.10C / v2 26.07C / raw (1988-2017) 26.29C

v1 warmed 0.32C / v2 warmed 0.53C

1961-90 - v1 25.79C / v2 - 25.55C

2016-2017 - 25.90C

acorn 2 dalwallinu minimum temperatures

1957-1978/86 - v1 12.13C / v2 11.21C / raw (1957-87) 12.20C

1979/87-2011/17 - v1 12.21C / v2 11.61C / raw (1988-2017) 12.20C

v1 warmed 0.08C / v2 warmed 0.40C

1961-90 - v1 12.12C / v2 - 11.34C

2016-2017 - 11.49C

Esperance

acorn 2 esperance maximum temperatures

1910-1963 - v1 21.16C / v2 21.01C / raw 21.19C

1964-2017 - v1 21.62C / v2 21.57C / raw 21.85C

v1 warmed 0.46C / v2 warmed 0.56C

1961-90 - v1 21.43C / v2 - 21.31C

2016-2017 - 21.69C

acorn 2 esperance minimum temperatures

1910-1963 - v1 11.30C / v2 10.96C / raw 11.44C

1964-2017 - v1 12.00C / v2 11.98C / raw 12.05C

v1 warmed 0.70C / v2 warmed 1.02C

1961-90 - v1 11.80C / v2 - 11.77C

2016-2017 - 12.14C

Eucla

acorn 2 eucla maximum temperatures

1914-1978 - v1 23.06C / v2 22.06C / raw 22.08C

1979-2017 - v1 23.22C / v2 23.12C / raw 23.39C

v1 warmed 0.16C / v2 warmed 1.06C

1961-90 - v1 22.70C / v2 - 22.36C

2016-2017 - 23.59C

Note - Eucla averages are unreliable because there are large numbers of consecutive days with missing temperatures, and these have been deleted in this analysis.

acorn 2 eucla minimum temperatures

1914-1978 - v1 11.72C / v2 11.68C / raw 12.17C

1979-2017 - v1 12.37C / v2 12.39C / raw 12.32C

v1 warmed 0.65C / v2 warmed 0.71C

1961-90 - v1 12.25C / v2 - 12.34C

2016-2017 - 12.20C

Note - Eucla averages are unreliable because there are large numbers of consecutive days with missing temperatures, and these have been deleted in this analysis.

Forrest

acorn 2 forrest maximum temperatures

1947-1981 - v1 25.34C / v2 25.39C / raw 25.37C

1982-2017 - v1 25.99C / v2 25.98C / raw 26.08C

v1 warmed 0.65C / v2 warmed 0.59C

1961-90 - v1 25.49C / v2 - 25.42C

2016-2017 - 26.13C

acorn 2 forrest minimum temperatures

1947-1981 - v1 10.20C / v2 9.65C / raw 9.77C

1982-2017 - v1 10.88C / v2 10.63C / raw 10.91C

v1 warmed 0.68C / v2 warmed 0.98C

1961-90 - v1 10.43C / v2 - 9.84C

2016-2017 - 10.88C

Geraldton

acorn 2 geraldton maximum temperatures

1910-1963 - v1 25.52C / v2 25.04C / raw 25.10C

1964-2013/2017 - v1 25.84C / v2 25.80C / raw 26.11C

v1 warmed 0.32C / v2 warmed 0.76C

1961-90 - v1 25.54C / v2 - 25.32C

2016-2017 - 26.33C

acorn 2 geraldton minimum temperatures

1910-1963 - v1 13.28C / v2 13.01C / raw 14.35C

1964-2013/2017 - v1 13.62C / v2 13.56C / raw 13.67C

v1 warmed 0.34C / v2 warmed 0.61C

1961-90 - v1 13.52C / v2 - 13.43C

2016-2017 - 13.23C

Giles

acorn 2 giles maximum temperatures

1957-1986 - v1 29.27C / v2 28.78C / raw 29.21C

1987-2007/2017 - v1 29.55C / v2 29.47C / raw 29.60C

v1 warmed 0.28C / v2 warmed 0.69C

1961-90 - v1 29.28C / v2 - 28.78C

2016-2017 - 29.92C

acorn 2 giles minimum temperatures

1957-1986 - v1 15.46C / v2 16.13C / raw 15.69C

1987-2017 - v1 15.85C / v2 16.10C / raw 16.06C

v1 warmed 0.39C / v2 cooled 0.03C

1961-90 - v1 15.41C / v2 - 16.02C

2016-2017 - 15.76C

Halls Creek

acorn 2 halls creek maximum temperatures

1910-1963 - v1 33.65C / v2 32.33C / raw 33.55C

1964-2017 - v1 33.80C / v2 33.03C / raw 33.55C

v1 warmed 0.15C / v2 warmed 0.70C

1961-90 - v1 33.94C / v2 - 32.75C

2016-2017 - 34.33C

acorn 2 halls creek minimum temperatures

1910-1963 - v1 19.47C / v2 20.22C / raw 18.28C

1964-2017 - v1 20.16C / v2 20.08C / raw 20.12C

v1 warmed 0.69C / v2 cooled -0.14C

1961-90 - v1 20.13C / v2 - 19.99C

2016-2017 - 20.50C

Kalgoorlie

acorn 2 kalgoorlie maximum temperatures

1910-1963 - v1 24.99C / v2 24.53C / raw 25.56C

1964-2017 - v1 25.36C / v2 24.98C / raw 25.39C

v1 warmed 0.37C / v2 warmed 0.45C

1961-90 - v1 25.20C / v2 - 24.78C

2016-2017 - 24.92C

acorn 2 kalgoorlie minimum temperatures

1910-1963 - v1 11.88C / v2 11.51C / raw 11.98C

1964-2017 - v1 12.24C / v2 12.25C / raw 11.93C

v1 warmed 0.37C / v2 warmed 0.45C

1961-90 - v1 12.14C / v2 - 12.20C

2016-2017 - 12.15C

Katanning

acorn 2 katanning maximum temperatures

1910-1963 - v1 21.80C / v2 21.54C / raw 21.99C

1964-2011/2017 - v1 22.26C / v2 22.01C / raw 22.28C

v1 warmed 0.46C / v2 warmed 0.47C

1961-90 - v1 22.14C / v2 - 21.72C

2016-2017 - 21.76C

acorn 2 katanning minimum temperatures

1910-1963 - v1 9.03C / v2 8.41C / raw 9.37C

1964-2011/2017 - v1 9.30C / v2 9.38C / raw 9.47C

v1 warmed 0.27C / v2 warmed 0.97C

1961-90 - v1 9.29C / v2 - 9.25C

2016-2017 - 9.30C

Learmonth

acorn 2 learmonth maximum temperatures

1976-1996 - v1 31.65C / v2 31.71C / raw 31.70C

1997-2017 - v1 32.07C / v2 32.07C / raw 32.10C

v1 warmed 0.42C / v2 warmed 0.36C

2016-2017 - 32.32C

acorn 2 learmonth minimum temperatures

1976-1996 - v1 17.63C / v2 17.42C / raw 17.69C

1997-2017 - v1 17.75C / v2 17.75C / raw 17.78C

v1 warmed 0.12C / v2 warmed 0.33C

2016-2017 - 17.63C

Marble Bar

acorn 2 marble bar maximum temperatures

1910-1963 - v1 34.90C / v2 34.77C / raw 35.48C

1964-2017 - v1 35.13C / v2 35.14C / raw 35.25C

v1 warmed 0.23C / v2 warmed 0.37C

1961-90 - v1 34.97C / v2 - 35.02C

2016-2017 - 35.97C

acorn 2 marble bar minimum temperatures

1910-1963 - v1 19.63C / v2 19.16C / raw 19.74C

1964-2017 - v1 19.95C / v2 19.66C / raw 20.32C

v1 warmed 0.32C / v2 warmed 0.50C

1961-90 - v1 19.58C / v2 - 19.23C

2016-2017 - 20.93C

Meekatharra

acorn 2 meekatharra maximum temperatures

1927-1971 - v1 28.35C / v2 28.54C / raw 28.85C

1972-2017 - v1 29.03C / v2 29.04C / raw 29.24C

v1 warmed 0.68C / v2 warmed 0.50C

1961-90 - v1 28.48C / v2 - 28.50C

2016-2017 - 29.66C

acorn 2 meekatharra minimum temperatures

1927-1971 - v1 15.65C / v2 15.14C / raw 15.29C

1972-2017 - v1 16.22C / v2 15.88C / raw 16.10C

v1 warmed 0.57C / v2 warmed 0.74C

1961-90 - v1 16.10C / v2 - 15.52C

2016-2017 - 16.20C

Merredin

acorn 2 merredin maximum temperatures

1915-1965 - v1 24.48C / v2 24.76C / raw 24.63C

1966-2017 - v1 25.21C / v2 25.28C / raw 25.14C

v1 warmed 0.73C / v2 warmed 0.52C

1961-90 - v1 24.75C / v2 - 24.89C

2016-2017 - 25.17C

acorn 2 merredin minimum temperatures

1915-1965 - v1 10.42C / v2 10.68C / raw 10.56C

1966-2017 - v1 11.41C / v2 11.41C / raw 11.44C

v1 warmed 0.99C / v2 warmed 0.73C

1961-90 - v1 11.27C / v2 - 11.31C

2016-2017 - 11.19C

Morawa

acorn 2 morawa maximum temperatures

1926-1969 - v1 26.57C / v2 26.59C / raw 27.25C

1970-2017 - v1 27.62C / v2 27.71C / raw 27.83C

v1 warmed 1.05C / v2 warmed 1.12C

1961-90 - v1 26.85C / v2 - 27.04C

2016-2017 - 27.68C

Note - Morawa averages are unreliable because there are large numbers of consecutive days with missing temperatures, and these have been deleted in this analysis.

acorn 2 morawa minimum temperatures

1926-1969 - v1 11.72C / v2 11.81C / raw 11.97C

1970-2017 - v1 12.58C / v2 12.65C / raw 12.91C

v1 warmed 0.86C / v2 warmed 0.84C

1961-90 - v1 12.32C / v2 - 12.42C

2016-2017 - 12.44C

Note - Morawa averages are unreliable because there are large numbers of consecutive days with missing temperatures, and these have been deleted in this analysis.

Perth

acorn 2 perth maximum temperatures

1910-1963 - v1 24.35C / v2 23.88C / raw 23.42C

1964-2017 - v1 24.83C / v2 24.82C / raw 24.67C

v1 warmed 0.48C / v2 warmed 0.94C

1961-90 - v1 24.58C / v2 - 24.51C

2016-2017 - 24.83C

acorn 2 perth minimum temperatures

1910-1963 - v1 11.55C / v2 11.20C / raw 12.49C

1964-2017 - v1 12.13C / v2 11.94C / raw 12.40C

v1 warmed 0.58C / v2 warmed 0.74C

1961-90 - v1 11.98C / v2 - 11.67C

2016-2017 - 12.34C

Port Hedland

acorn 2 port hedland maximum temperatures

1913-1965 - v1 32.73C / v2 33.42C / raw 32.16C

1966-2017 - v1 33.20C / v2 33.53C / raw 33.40C

v1 warmed 0.47C / v2 warmed 0.11C

1961-90 - v1 32.89C / v2 - 33.50C

2016-2017 - 34.08C

acorn 2 port hedland minimum temperatures

1913-1965 - v1 18.68C / v2 19.16C / raw 19.92C

1966-2017 - v1 19.65C / v2 19.69C / raw 19.70C

v1 warmed 0.97C / v2 warmed 0.53C

1961-90 - v1 19.20C / v2 - 19.35C

2016-2017 - 20.84C

Wandering

acorn 2 wandering maximum temperatures

1910-1963 - v1 22.60C / v2 22.37C / raw 22.88C

1964-2017 - v1 23.18C / v2 22.96C / raw 23.49C

v1 warmed 0.58C / v2 warmed 0.59C

1961-90 - v1 22.82C / v2 - 22.59C

2016-2017 - 23.06C

acorn 2 wandering minimum temperatures

1910-1963 - v1 7.54C / v2 7.66C / raw 8.27C

1964-2017 - v1 8.23C / v2 8.23C / raw 8.76C

v1 warmed 0.69C / v2 warmed 0.57C

1961-90 - v1 7.99C / v2 - 8.00C

2016-2017 - 8.51C

Wittenoom

acorn 2 wittenoom maximum temperatures

1952-1984 - v1 32.74C / v2 32.10C / raw 32.71C

1985-2017 - v1 33.19C / v2 33.14C / raw 33.21C

v1 warmed 0.45C / v2 warmed 0.61C

1961-90 - v1 32.85C / v2 - 32.29C

2016-2017 - 33.67C

acorn 2 wittenoom minimum temperatures

1952-1984 - v1 19.54C / v2 19.37C / raw 19.64C

1985-2017 - v1 19.93C / v2 19.96C / raw 19.92C

v1 warmed 0.39C / v2 warmed 0.59C

1961-90 - v1 19.63C / v2 - 19.47C

2016-2017 - 20.37C

Download Excel spreadsheet sorted daily maximum temperatures for all WA weather stations in ACORN 1 and ACORN 2 (PDF 32.0mb)

Download Excel spreadsheet sorted daily minimum temperatures for all WA weather stations in ACORN 1 and ACORN 2 (PDF 32.0mb)

Download Excel spreadsheets below for WA weather stations with annualised maximum and minimum temperatures in ACORN 1 and ACORN 2

Albany

Bridgetown

Broome

Cape Leeuwin

Carnarvon

Cunderdin

Dalwallinu

Esperance

Eucla

Forrest

Geraldton

Giles

Halls Creek

Kalgoorlie

Katanning

Learmonth

Marble Bar

Meekatharra

Merredin

Morawa

Perth

Port Hedland

Wandering

Wittenoom




Top of page
Website home


Bookmark and Share


This website produced by Scribeworks 2009/19

Home