What are the prevailing winds, and what particular role do the hot winds play?
A general statement is not sufficient, for the winds vary much at different places; but taking the colony as a whole, its prevailing winds come from some point between north-west and south-west, and hence the dry climate. In Sydney no less than 39.6 per cent, of the wind comes from this quarter. The winds known as southerly bursters are generally to be expected from November to the end of February; they are always attended with strong electrical excitement, a stream of sparks being sometimes produced for an hour at the electrometer. The approach of the true burster is indicated by a peculiar roll of clouds, which, when once seen, cannot be mistaken. It is just above the south horizon, and extends on either side of it 15° or 20°, and looks as if a thin sheet of cloud were being rolled up like a scroll by the advancing wind. The change of wind is sometimes very sudden; it may be fresh N.E. and in ten minutes a gale from S. Hence vessels not on the look-out are sometimes caught unprepared, and suffer accordingly. When a southerly wind commences anywhere south of Sydney it is at once telegraphed to its principal coast towns, and a signal put up indicating its approach. As to the hot winds, they are so insignificant in number that it cannot be said they play any particular role. Their effect is to raise the temperature, because they flow from the heated interior of Australia; but they do not last long, and for the majority of people are dry, healthy winds. Indeed, they are by no means so oppressive as the warm northeast wind, so charged with moisture, which comes in the summer.
In summer the N. winds blow to the extent of 8 per cent., the S.W. winds 24.1 per cent., and the S. winds 20.4 per cent. Northerly, or warm-quarter winds, in summer are20 percent., and southerly, or cool-quarter winds, 6-4 per cent. The northerly winds in winter, however, are bleak and cold, like easterly winds in England. The particular role played by the hot wind is to precede a cyclonic movement, and is always in front of a low pressure area or V-shaped depression. It is frequently followed by thunderstorms and rain of short duration. It dries the surface and raises dust storms when strong. So far as its effects on the people are concerned, it does not appear to hinder the ordinary occupations of life. Some invalids are better during its continuance, some worse; but all weakly people feel some depression after "the change " comes. The aged are generally better in hot winds, unless they suffer from disease.
As far as the southern regions of the colony are concerned, we may say, speaking generally, that light winds and calms are a very distinctive characteristic. The prevailing wind in the summer is the S.E., varied by sea-breezes during the day. In the winter there are mostly dry, cold N.E. winds, broken at intervals by westerly and S.W. gales of moderate strength, squalls, and rain. The best and heaviest rainfalls are those which set in with the surface winds at N.E., the rain increasing in intensity as the wind veers to N.W., and breaking up into showers and squalls as it veers to S.W. In the interior, north of, say, latitude 30° to about 18° S., the prevailing wind all the year is the S.E. North of latitude 18° to the north coast the country is well within the influence of the north-west monsoon during the summer months, with frequent thunderstorms and heavy rains; and during the winter dry S.E. winds prevail.
Eastern Queensland (or rather the Pacific Slope) is very seldom troubled with hot winds. The hot winds of "continental" Queensland are always very dry, and are usually accompanied by dust storms.