Blacktown, nestled in New South Wales, Australia, showcases a distinctive climate classified as humid subtropical (Köppen: Cfa/Cfb, Trewartha: Cfbl/Cfal), marked by its blend of moderately hot, rainy summers and cold, moderately dry winters, with precipitation occurring throughout the year. Unlike Sydney Observatory Park, Blacktown experiences a greater annual temperature range between winter and summer, coupled with less precipitation.

Summers in Blacktown are characterized by moderate heat and humidity, comparable to Port Jackson, yet distinguished by a higher diurnal temperature range due to the absence of coastal sea breezes from the Tasman Sea. This lack of maritime influence extends summer temperatures, with approximately 29.6 days exceeding 30 °C (86 °F), more than double the occurrences observed in Observatory Park. Temperature extremes during summer span from 41.7 °C (107.1 °F) to 8.3 °C (46.9 °F).

In contrast, winters in Blacktown are cold and relatively dry, influenced by its inland location away from the Tasman Sea. Winter nights often dip below 5 °C (41 °F), with occasional frosty mornings. Southwesterly winds, known as frontal lows, frequently impact the region during winter, although they tend to lose moisture over the Victorian Alps and Great Dividing Range, resulting in the driest season for Blacktown. Winter temperature extremes range from 27.8 °C (82.0 °F) to –3.9 °C (25.0 °F).

Overall, Blacktown's climate paints a unique picture of seasonal dynamics, reflecting its inland position and distinct topographical features, contributing to the city's diverse weather patterns throughout the year.