Northern Australian temperature outlook
Issued 19 June 2013
The outlook for daytime temperatures shows a greater than 60% chance of exceeding the median maximum temperature across the Top End of the NT and Cape York Peninsula in Queensland. Probabilities exceed 80% along areas adjacent to the north coast (see map above).
Probabilities drop below 40% across southern Queensland and the southwest NT. This means that there is more than a 60% percent chance that daytime temperatures will be cooler than what is typical for July to September.
Night-time temperatures in the southern regions show no strong tendency towards being warmer or cooler than average. The chances of July to September minimum temperatures exceeding the long-term median are greater than 60% across the northern half of the NT and Cape York Peninsula in Queensland.
A negative Indian Ocean Dipole (IOD) event is favoured to develop during the northern dry season. A negative IOD during the dry season increases the chances of above normal humidity levels and rainfall (and thus cloud amount) over central and northern Australia. Increased cloudiness reduces sunshine hours, and hence daytime temperatures, and also acts as a blanket during the night, keeping night-time temperatures higher than average.
The tropical Pacific has remained ENSO-neutral since mid-2012. The dynamical seasonal outlook model indicates an increased likelihood of La Niña forming during the next few months. However, international climate models surveyed by the Bureau of Meteorology suggest ENSO-neutral is the most likely outcome over the coming season, with the Bureau model showing stronger odds than most of a weak La Niña.
How accurate is the outlook?
Outlook accuracy is related to how consistently the oceans and broadscale climate affect Australian temperatures. During the July to September period, historical accuracy shows the outlook for both maximum temperatures and minimum temperatures to be moderately consistent over most of northern of Australia. However, it is weak to very weakly consistent along the southern border of the NT, and parts of southern Queensland and Cape York Peninsula for minimum temperatures.