SYDNEY (Reuters) - Australia's record-breaking heatwave has sent temperatures soaring, melting road tar and setting off hundreds of wildfires - as well as searing new colors onto weather maps.

The Australian Bureau of Meteorology has added dark purple and magenta to its color-coded weather forecasting map to represent temperatures of 51 to 54 degrees Celsius (123.8 to 129.2 Fahrenheit), officials said.

Temperatures on the map were previously capped at 50 degrees Celsius, represented by the color black.

"In order to better understand what temperatures we might see ... we introduced two new colors," said Aaron Coutts-Smith, manager of climate services at the Bureau of Meteorology.

Forecast models have predicted a large area of temperatures of over 50 for next Monday, he added.

Australia's average maximum temperature has exceeded 39 degrees Celsius for a record-breaking seven consecutive days. The previous record of four consecutive days above that level was in 1973.

The hottest temperature recorded on Monday was in the South Australian outback town of Oodnadatta, where the mercury topped out at a scorching 48.2 degrees Celsius - forcing the local petrol station to stop selling fuel after it started vaporizing.

(Reporting By Thuy Ong, editing by Elaine Lies and Paul Tait)