Main points:
* Large diurnal temperature range - warmer than average days, cooler than average nights
* 10th warmest winter on record for statewide average maximum temperatures
* 12th coldest winter on record for statewide average minimum temperatures
* Coastal NSW recorded average to above average rainfall
* Central/southern slopes of the Great Divide and southern border areas of the state received below to very much below average rainfall
Winter 2006
Temperatures:
NSW experienced large diurnal temperature ranges during winter with warm days and cool nights. The statewide average maximum temperature was 0.82ºC above the historical average1 of 16.1ºC , making this the 10th warmest winter on record (statewide averages calculated 1950-2006). Maximum temperatures were above average over much of the east and south of the state with a band of very much above average temperatures stretching along the almost the entire western slopes of the Great Divide. This distribution of above average temperatures is a result of easterly wind anomalies across the state during much of winter. Southern areas on the western slopes of the divide which usually are affected by strong cool westerlies which ascend over the ranges producing cloud and rain instead frequently experienced dry, warm, descending easterly winds. The combination of these warm, dry easterly winds and warm northwesterly winds from the abnormally hot, dry interior resulted in high maximum temperatures on the south west slopes of the Great Divide. Small areas of the southern Riverina and Central West Slopes recorded their highest average winter maximum temperatures on record.
The statewide average minimum was 0.52 ºC below the average of 4.2 ºC, making this the 12th coldest winter on record (1950-2006). Below average minumum temperatures were recorded across most of the south and west of the state. Very much below average winter minimum temperatures were experienced in the Lower Western, Riverina, Sydney Metropolitan, Illawarra and Central Tablelands. The far south coast was the only area of the state to record above average minimum temperatures (See Map 2). The distribution of very much below average temperatures is a result of the dry conditions and clear night skies during winter. The lack of cloud has enabled much stronger radiative cooling overnight than would be normally expected, resulting in much lower than average minimums across large areas of the state.
Rainfall:
Winter rainfall was varied throughout the state in 2006. The central and southern slopes west of the Great Divide and the southern border regions of the state recorded below average winter rainfall. The southern half of the Southwest Slopes received very much below average rainfall. This distribution of below average rainfall is a result of weaker than average westerly wind flow across the state with a below average frequency of rain bearing winter cold fronts. The Upper Western and areas along the entire coast of NSW recorded above average winter rainfall. This pattern is a result of high pressure systems positioned much further south than normal through most of winter. Moist onshore easterly winds on the northern side of the high pressure systems brought with them enhanced coastal winter rainfall (See Map 3). The statewide average rainfall for winter 2006 of 105.6mm was slightly below the average of 115.1mm.
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