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Blacktown is one of Sydney's largest suburbs by population, sprawling across the Cumberland Plain roughly 35 kilometres west of the CBD. Its flat terrain and distance from the coast produce a climate characterised by hot summers, cool winters, and pronounced daily temperature swings. Average summer maximums reach 30-32 degrees Celsius, several degrees above the coastal fringe, while winter minimums drop to 4-6 degrees with regular frost. The Blacktown area records approximately 10-15 more days per year above 35 degrees than eastern suburbs like Bondi, placing it firmly in Sydney's western heat belt alongside Parramatta and Penrith.
Blacktown receives around 850 millimetres of rainfall annually, below the metropolitan average but sufficient to sustain the remnant Cumberland Plain woodland in areas like Nurragingy Reserve. Rainfall is heavily skewed toward summer thunderstorms, which can drop 30-50 millimetres in a single event. The suburb straddles the Eastern Creek and Toongabbie Creek catchments, both of which are prone to flash flooding during intense rainfall. The March 2021 floods caused significant disruption across Blacktown, with residential streets near creek lines inundated. Winter rainfall is lower and steadier, delivered by cold fronts tracking across the southern Tasman Sea.
One of Blacktown's most notable weather characteristics is its large diurnal temperature range, the gap between the daily maximum and minimum. On a typical summer day this range can exceed 15 degrees, compared to just 6-8 degrees at Bondi. This occurs because the flat, open terrain cools rapidly after sunset through radiative heat loss, while the lack of nearby water bodies means there is no thermal reservoir to moderate overnight temperatures. In winter the effect is even more pronounced, with clear nights allowing temperatures to plummet from a pleasant 17-degree afternoon to near-freezing by dawn. The urban heat island effect is less intense in Blacktown's spread-out residential areas than in the compact CBD of Parramatta.
Blacktown sits squarely in Sydney's thunderstorm alley, the corridor running from the Blue Mountains foothills east through western Sydney where afternoon storms are most frequent and intense. Between October and March, thunderstorms affect Blacktown on average 25-30 days, producing heavy rain, lightning, and occasionally destructive hail and wind gusts. The November 2021 supercell event brought golf-ball-sized hail across Blacktown, damaging thousands of cars and homes. Thunderstorm downbursts, sudden outflows of cold air that produce damaging surface winds, are a recurring risk in the flat terrain. The Bureau of Meteorology monitors this corridor closely during the storm season, issuing severe thunderstorm warnings that frequently cover the Blacktown area.
Blacktown is typically at or beyond the westernmost limit of the afternoon sea breeze. On many summer days the sea breeze fails to reach Blacktown entirely, leaving the suburb under hot, still conditions until a southerly change arrives, often well after sunset. When the sea breeze does penetrate, usually on days when the synoptic-scale wind pattern is supportive, it brings welcome relief, dropping temperatures by 5-7 degrees. Westerly winds dominate in winter, flowing off the Blue Mountains and across the Cumberland Plain. These westerlies can be cold and dry, particularly in the early morning. Spring and early summer bring periodic northwesterly events ahead of cold fronts, which are the most fire-weather-prone wind pattern for the western suburbs.
Blacktown occupies a middle ground between Penrith's extremes and the slightly milder conditions of Parramatta. It shares the western suburbs' hot-summer, cool-winter profile but avoids Penrith's most extreme heat due to being 20 kilometres further east. Compared to the coastal suburbs, Blacktown receives roughly 30 percent less annual rainfall, 50 percent more days above 35 degrees, and significantly more frost. Wind speeds are lower on average than at the coast, but storm-related gusts can be more severe due to the prevalence of supercell thunderstorms in the area. For residents, Blacktown's weather means genuine four-season living with more extreme heat management required than Sydney's beachside suburbs.
See how Blacktown's weather compares to its neighbours: Parramatta weather, Penrith weather and Liverpool weather. Or browse all Sydney suburb forecasts.