Australian Monthly Climate Summary: December 2007
Thursday 3rd January, 2008
Rainfall was generally average to above average over much of the country, with above-normal rainfall in all states and territories. The above average totals removed short-term deficiencies in eastern Australia. Temperatures were near normal across much of the country, with warm overnight minima generally offsetting cool daytime maxima, a typical pattern for a wet month. Mean temperatures averaged across Australia were slightly below normal (anomaly −0.12°C).
Daytime maximum temperatures were below normal throughout much of the continent, except for the southern central and eastern parts which recorded above average daytime temperatures. Anomalies of −2 to −3°C were widespread over southern WA and southern Queensland and northern NSW, with southern Queensland and northern NSW recording mean maximum anomalies down to −4°C over a wide area. Much of WA and southern Queensland into northern NSW recorded very much below average temperatures (decile 1), it was the sixth coolest December on record for WA. Southwest Victoria and much of Tasmania recorded very much above average (decile 10) temperatures, making it the third warmest December on record for the state; maxima in Victoria was the ninth highest.
Anomalies of overnight minimum temperatures showed a somewhat different pattern to those of daily maxima, with weak warm anomalies generally in the central and eastern parts and cool anomalies over much of WA. Anomalies between +1 and +2°C covered much of Tasmania, Victoria, NSW, and the NT, with an area of very much above average minimum temperatures over Tasmania, central Victoria and southern NSW. The extreme northern coast of Tasmania recorded highest on record minimum temperatures for the month, making it the fourth warmest November on record for Tasmania. In contrast much of WA was below average with a small area of overnight anomalies below −3°C.
In terms of mean temperatures, WA and southern Queensland into northern NSW was generally below average, with Tasmania, Victoria, southern SA and eastern NSW generally above average. Much of the rest of Australia was slightly above average. Small areas in central WA were very much below average, whilst Tasmania, central and southern Victoria and a small area in northern Queensland recorded very much above average mean temperatures. Areas in the northern corners of Tasmania recorded highest on record mean temperatures. It was the third warmest December in Tasmania in terms of mean temperatures and the seventh warmest in Victoria.
* Anomaly is the difference from the long-term average
Above-normal falls were widespread across Australia during December, with the highest totals in eastern and northern Australia and in eastern WA. Large areas in NSW and central Queensland, and in the southern half of WA into SA, had falls in the highest decile. Notably, a large area in northern NSW recorded highest on record falls for the month. Above average falls were also recorded in the northern parts of the NT and in Victoria and western Tasmania. As a whole, Australian rainfall was 40% above normal for the month, furthermore, all states and territories were wetter than normal, WA and NSW were 84% and 77% wetter than normal respectively.
Very few parts of Australia recorded below normal rainfall, an area on the southeast coast of Queensland into northeastern NSW, southern NT, eastern Tasmania and notably northern Cape York Peninsula. Northern Cape York Peninsula was the only area to record very much below average rainfall, with a small area recording lowest on record falls.