Heat waves feature prominently in the climate of southern Australia. Their impact can be felt in terms of human health and as a strain on the economy. Considering this, a synoptic scale climatological assessment has been undertaken on heat waves in Melbourne, Adelaide and Perth. An automatic tracking scheme is used to track cyclones and anticyclones at both upper and lower levels which are associated with heat waves in this region. Results show that heat waves are typically induced and maintained by a blocking high and they can frequently become enhanced from a developing cyclone. The heat wave inducing anticyclones often originates from the western Indian Ocean, whereas cyclones, if involved, are usually developed relatively locally as heat lows. In the heat waves in which cyclones have an impact, the cyclones are capable of reinforcing the west of the upper level blocking ridge through hot and dry advection. The upper level anomalies which induce the blocking high also show a high level of mobility preceding the event. However this is not seen in the upper level tracks, which seem to reflect the strength of the blocking ridge.

We also show that there is a significant air-sea interaction preceding these strong heat wave events. An increase in the meridional temperature gradient over the Indian Ocean acts to enhance the upper level Rossby waves via an enhanced baroclinicity. Also, local effects such as cooling of the waters close to the Australian coast help maintain the blocking highs formed over the region.