Mean annual temperatures in the region range from very cool to warm; from just up to depending on altitude and latitude. The range in annual rainfall is likewise great; from just on the far western plain around
Griffith, to as much as on the western face of the
Snowy Mountains at
Cabramurra. Depending on latitude, rainfall peaks in either winter or spring; the more southern and mountainous areas show a distinct winter peak, as opposed to one of springtime. High summer to mid autumn is usually the driest period and is prone to severe drought. Snow is common on the higher slopes above an altitude of approximately in the southern boundary of the region; and above in the northern boundary, but may occur as low as or less. Snow has been recorded on several occasions to fall and settle as low as
Albury and
Wagga Wagga, and respectively; and on three occasions as low as
Narrandera to the north-west, .
Sleet is a regular occurrence throughout the higher parts of the region, and occurs even in the lowland areas – especially in the south. This region features the greatest seasonal range of maximum temperatures than any other in Australia, with some places ranging as much as 20 °C in maximum temperatures between January and July. This is due to being
windward of the Great Dividing Range, with the prevailing westerly airmasses and accompanying cloud cover bringing low maximum temperatures in winter; and the far inland location, prolonging heatwaves in summer. These areas have a climate that is more similar to that of
Adelaide and
Perth, than the proximate cities like
Sydney and
Wollongong, with their wet winters and relatively dry summers.
Forecast area for Bureau of Meteorology The
South West Slopes forecast area used by the
Bureau of Meteorology includes only a region stretching approximately between
Young and
Tumbarumba from north to south. The area is much smaller than that defined as a bioregion by the
NSW National Parks & Wildlife Service, as the Bureau of Meteorology has split this bioregion into three additional forecast districts: the
Central West Slopes & Plains, constituting the northern parts of the bioregion; as well as
North East (Victoria) and
Riverina, which constitute the remaining south and west of the bioregion. ==Flora and fauna==