The north-east loop moves gradually westward and southward during spring and summer, forming finally a broad warm loop running down from the Gulf to South-west Queensland. This trend of the loop is no doubt largely due to the monsoon winds from the north, which characterize the front of the cyclonic system usually dominating North-west Australia in summer.
In April and later, the Queensland loop shrinks as the land areas cool, while the Kosciusko Alpine loop (in the S.E.) advances to its maximum in July.
Across Central and South-western Australia the isotherms move equator-wards in winter, and retreat in summer without losing their east-west direction. The 75° isotherm moves about 1,200 miles north (as winter approaches) from January to July, the cooling being quickest in April and May. (It must be noticed that our meteorological knowledge of the west centre of the continent is very meagre, and more complete data may indicate looped isotherms in the remaining quadrant of the continent, though the topography would not seem to favour such a condition.)
Details of the distribution of temperature, especially with regard to the State capitals, will be of interest.
January is the hottest and July the coldest month.
The highest temperatures are recorded over the north-western portion of Western Australia (see Fig. 14), where the maximum shade temperatures have exceeded 100° on 64 consecutive days and 90° on 150 consecutive days, the mean temperature of the hottest month being 90° and the mean temperature of the coldest 65°.
Fig. 14.
Chart showing maximum number of consecutive days with temperature reaching 90° for any one hot spell.
