This report documents variation of summer temperatures across the Local Government Area of Penrith in Western Sydney. Between 14 December 2019 and 31 March 2020, more than 1.4 million measurements of air temperatures were collected using 120 data loggers. The network of data loggers covered the entire Local Government Area from Emu Plains in the west to St Marys in the east and Agnes Banks in the north to Badgerys Creek in the south. Analyses of these data revealed that local populations of Penrith experienced air temperatures of more than 50°C during three individual days.Throughout the summer of 2019/20, Emu Plains was the warmest and Mulgoa the coolest suburb. Nighttime air temperatures were higher in suburbs with high cover of hard surfaces compared to those where open surfaces dominated, demonstrating clear Urban Heat Island Effects in the area. An Urban Heat Island was also detected for the town of St Marys, where the urban core remained up to 2.4°C warmer during the night compared to the surrounding residential neighbourhoods. A wide rage of temperature analyses provide a nuanced picture of how summer heat is impacting this important city in Western Sydney. A total of 12 clear recommendations developed with the help of the empirical work.