 This study analyses changes in spatial characteristics of contiguous heat waves in Australia during 1958 to 2020 using observational data and a large multi-member ensemble of a physical climate model. The results show that extremely large contiguous heat waves are covering significantly larger areas and getting significantly longer during the recent period compared to the historical period. Additionally, the study found that aerial magnitude, total area, median duration, and maximum area of large and extremely large contiguous heat waves in Australia are significantly higher, lower, during strong El Nino seasons relative to neutral seasons. The large-scale physical mechanisms driving these heat waves include antipsychonic highs over the southeast and psychonic lows over the northwest of Australia. This article was offered by P. Jyotish Kumar Reddy, Sarah E. Perkins Kirkpatrick and Jason J. Shapples.