Annual Climate Report 2004
The Annual Climate Report is the Bureau of Meteorology's official historical record of the previous year's climate. It provides a national overview of temperature and rainfall during the year, and documents significant weather and climate events.
This report contains an in-depth analysis of the past year's climate, following on from the Annual Climate Statement released earlier in the year.
Australia in 2004 again experienced warmer than normal conditions across most of the country. Preliminary data indicate that the all-Australian annual mean temperature for 2004 was 0.45 °C above the 1961–90 long-term average, making it the tenth warmest year since 1910, when reliable Australia-wide climate records became available. Daytime temperatures contributed more of the anomalous warmth than overnight temperatures: the annual mean maximum temperature was 0.51 °C above normal (tenth highest), and the mean minimum temperature 0.39 °C above normal (eleventh highest). The annual values were boosted by several extensive warm spells, including an exceptional two-week heat-wave during February, which affected a large proportion of the continent and resulted in many new temperature records, and warm periods in eastern Australia during September and October.
Australian mean temperatures are calculated from a country-wide network of about 100 high-quality, mostly rural, observing stations that have been corrected for any artificial discontinuities caused by changes in instrumentation and location. Many of these sites are included in Australia's contribution to the Global Climate Observing System - a comprehensive, world-wide network of meteorological stations for monitoring long-term climate trends and variability.
The general rise in Australian temperatures during the second half of the 20th century is in line with global warming trends. According to a preliminary estimate released by the World Meteorological Organization (WMO) on 15th December 2004, the global mean temperature for 2004 was about 0.44 °C above normal, making it the fourth warmest year since records commenced in 1861.
Preliminary data indicate that the average rainfall throughout Australia for 2004 was 513 mm, which is higher than the long-term average of 472 mm. Rainfall patterns were far from uniform, however, with much of the western half of the country (apart from southwest WA) receiving above average rainfall for the year. The northern wet season was particularly active during January to March, with heavy rains occasionally associated with flooding, particularly in inland Queensland and northern New South Wales around mid-January, and in the Northern Territory in February and March. Despite good rainfall throughout southeast Australia in November and December, the annual totals across this region were mostly below normal. Consequently, 2004 rainfall has failed to alleviate the long-term deficiencies characterising rainfall patterns over much of southeast Australia in recent years. Some recording stations have now experienced an unprecedented eight consecutive years of below average rainfall. Australia's area-averaged rainfall is calculated from a network of around 6500 rainfall stations, most of which are staffed by volunteer observers.
Observations averaged over the total area of each State reveal that, when compared to normal, Western Australia was the wettest State, while Victoria was the driest. New South Wales had the highest departures from normal daytime temperatures and South Australia had the highest departures from normal overnight temperatures in 2004.
Product Code: IDCKGCAR1.2007