Weather and climate in NSW
The state of NSW is diverse. It has many landscapes and ecosystems, including the largest and highest alpine areas in Australia, extensive rangelands, and some of the country’s most productive agricultural areas, such as parts of the Murray–Darling Basin.
Temperature and rainfall in the state fluctuate greatly, with more variability in seasonal and regional climate than in many parts of the world. Heatwaves, storms, drought, floods and bushfires are all part of life in NSW, and they can have devastating effects on the environment as well as human life and property at great cost to the community.
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 based in south-western NSW where the recent droughts and now extensive floods show how sensitive our stocks of reliable water are to variability. The long coastal strip is home to most of the state’s population and many high-value assets that are susceptible to storm surges, sea level rise and increased flooding.
Climate varies across the state and across time
Although average temperatures across the state are generally mild, the arid north-west of NSW regularly records very high temperatures while alpine southern regions frequently fall below zero.
Annual average rainfall varies from less than 200 mm in north-western NSW to more than 1800 mm along the coast. Summer and winter rainfall is fairly evenly distributed over much of the state, as shown in the green area on the map. North-eastern NSW has relatively wet summers and dry winters, while southern districts receive little rain in summer, making agriculture, in particular, reliant on winter rains arriving via 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 temperatures and provide moisture for abundant rainfall. Moist onshore winds deposit significant precipitation on the steeply rising Great Dividing Range. The ranges enhance rainfall near the coast and contribute to a drop in annual rainfall from east to west across much of the state. The dry north-west of the state receives most of its highly variable rainfall in very irregular, high intensity rainfall events, that are more likely in summer but can occur at any time of the year.
Afternoon sea breezes usually moderate summer temperatures along coastal NSW. 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 the 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 Alps and 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 a highly variable climate from year to year. For short animations about how these drivers influence climate in NSW, see Climate Dogs.
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 is the usual period for estimating average climate, long enough to sample a full range of weather (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 the weather (or meteorological) data over time.
Page last updated: 31 October 2012