Despite the presence of La Niña, the winter and spring months of 1938 were extremely dry; southern Victoria, in fact, had its driest ever July-December period. As vegetation dried out, serious fires recurred throughout the normally fire-free spring months - as early as August a dangerous "crown" fire developed near Creswick. By January, most of Victoria was in an extremely hazardous condition.

In the first week of January 1939, an almost stationary high pressure system became established over the Tasman Sea, where it remained until the 14th. Very hot air from the continental interior was brought across southeastern Australia, with heat wave conditions in Victoria from the 6th to 13th (though weak cold fronts every two or three days brought temporary milder spells to the south). In Melbourne, 43.1°C was recorded on the 8th, and a record 44.7°C, on the 10th. On these days, many large fires broke out and spread fiercely, claiming 21 lives. Critically, these fires could not be extinguished, despite milder conditions in southern Victoria on the 11th and 12th.

Buildings ablaze in West Healesville, in Victoria's forest country, during the January 1939 fires (photo courtesy of the Victorian Dept of Natural Resources & Environment).

Sometimes in Melbourne, the night before the onset of severe fire weather conditions is calm and mild, as a shallow layer of stable air near the earth’s surface - known as an atmospheric inversion - insulates the city from hot air and strengthening winds aloft. Such was the night of the 12th in Melbourne. When the inversion broke on the morning of the 13th, temperature and wind-speed increased dramatically and relative humidity plummeted. At 12.30pm the temperature peaked at a new record 45.6°C. Under the influence of the strong, hot winds, fires already burning quickly coalesced into an ocean of flame. Timber towns such as Woods Point, Noojee, and Matlock were burnt to the ground, as extensive tracts of mountain ash forest (including Melbourne’s main catchment area) were incinerated. Many people were trapped in timber mills and burnt alive. Two fire fronts converged on Warrandyte, an outer Melbourne suburb, necessitating evacuations and causing heavy property losses. Huge fires also raged in southeastern South Australia, and over southwestern Victoria. In all, another 50 people died on "Black Friday". A cool change reached central Victoria in the early afternoon of the 13th (fortunately without squally winds, as occurred on Ash Wednesday), but virtually no rain accompanied the change.

Burnt mountain ash trees line Black's Spur Road between Healesville and Marysville, in Victoria's mountain forest country, following the Black Friday bushfires of 1939.
(photo courtesy of the Victorian Dept of Natural Resources & Environment).

The resulting Royal Commission into the fires headed by Justice Stretton found that most fires were caused by the uninformed actions of landowners and others, who routinely used fire in their activities. Many of the recommendations concerning the organisation and powers of rural fire fighting authorities in Victoria were eventually implemented.