Weather and climate in New South Wales
NSW has diverse landscapes and ecosystems, including Australia’s largest and highest alpine areas, part of the Murray-Darling Basin, extensive rangelands, and some of the nation’s most productive agricultural areas.
Temperature and rainfall fluctuate greatly, with large variability in seasonal and regional climatic conditions bringing heatwaves, storms, droughts, floods and bushfires, which can have devastating effects on the environment, human life and property.
Climate change will exacerbate natural variability, making it more difficult to manage our landscapes and ecosystems and the human activities that depend on them. Communities already affected by climate variability will be challenged by a climate shift, and there will be additional demands on our emergency services and health system.
Much of the state’s irrigated agriculture is located in the south-west, where the droughts and extensive floods have shown how sensitive our stocks of reliable water are to variability. The long coastal strip is home to most of the state’s population and to many high-value assets that are susceptible to storm surges, sea-level rise and increased flooding.
Climate varies across the state and across time
Average temperatures across the state are generally mild, although the arid north-west regularly records very high temperatures and those in the alpine southern regions frequently fall below zero.
Annual average rainfall varies from less than 200 mm in the north-west to more than 1800 mm along the coast. Summer and winter rainfall varies across the state (see map ‘Major seasonal rainfall zones of Australia’). The north-east has relatively wet summers and dry winters, whereas southern districts receive little rain in summer, making agriculture particularly reliant on rainfall from cold fronts and lows passing over south-eastern Australia during the winter growing season.
The seasonal pattern of rainfall varies across Australia—particularly in NSW, where four of the six major climate classes occur.
Source: Bureau of Meteorology.
The coast of NSW is influenced by the warm waters of the Tasman Sea, which moderate the temperature and provide moisture for abundant rainfall. Moist onshore winds deposit substantial amounts of precipitation on the steeply rising Great Dividing Range, enhancing rainfall near the coast but contributing to a decrease in rainfall moving from east to west. The dry north-west of the state receives most of its highly variable rainfall in very irregular, intense events, which are more likely in summer but can occur at any time.
Afternoon sea breezes usually moderate summer temperatures along the coast. In contrast, the arid north-west of the state regularly experiences maximum temperatures above 35°C during summer. Occasionally the heat from these desert regions is drawn south and east ahead of summer cold fronts, producing very hot conditions in southern and coastal districts. The very high temperatures, strong winds and low humidity ahead of these fronts increase the risk of bushfire. In winter, cold snaps may lead to inland frosts and snowfall on the Australian Alps and Southern Tablelands.
Climatic conditions can also change greatly over time. The major oceanic climate drivers—the El Niño Southern Oscillation, Southern Annular Mode and Indian Ocean Dipole—interact over NSW, producing wide variations in climate among years. How these drivers influence climate is explained in the Climatedogs short animations.
Climate versus weather
Climate is the set of averages, variations and extremes of weather in a region over long periods of time. Thirty years or more—long enough to sample a full range of weather—is the usual period for estimating average climate (Australian Academy of Science, 2010)
Weather describes the atmospheric conditions over defined short periods of time, such as hours or days.
Climate is often easier to predict than weather. For example, if you are asked on a Monday to predict whether it will be cooler on the following Monday, you could make a prediction but with little confidence.
However, if you were asked ‘Will the average monthly temperature for June next year be hotter or colder than for December?’ you would be certain that the average monthly temperature in December will be hotter than the average monthly temperature in June. This is because we understand seasonal climatic cycles and weather (or meteorological) data over time.