Summer is the wettest season while winter is the driest.
Surface wind speed and direction in the Penrith LGA is influenced by day to day changes in synoptic weather patterns and drainage basin topography. In the Sydney airshed as a whole, summer seabreezes and cold air drainage flows at night have a significant effect on weather and air quality conditions. To understand the form of the City of Penrith it must first be examined in the broader context in its relationship to the growth of the Sydney Metropolitan Region. The growth of Sydney prior to the second world war was limited to concentrated inner urban area and nodes along the railway lines radiating from the City Centre. Penrith was one of these activity nodes on the main western railway.