December 2019 was the driest December on record for Australia.
Rainfall deficiencies expanded and intensified with the area of lowest on record rainfall for some periods growing over eastern Australia.
It was the third-driest December on record for Victoria.
Eastern and most of western Victoria recorded very little rain, with large areas receiving less than 10 millimetres for the whole month.
It came off the back of close-to-average rainfall for most of the state in November, which followed a very dry October.
2019 was bookended by very warm days for Victoria - the warmest January and the second warmest December mean maximum temperatures on record.
Statewide, the monthly mean maximum temperature was 3.13 degrees warmer than the long-term December average.
While mean maximum temperatures for December were much warmer than average across most of Victoria, in the north they were highest on record, compounding the moisture stress.
The long-term rainfall deficiencies combined with the high temperatures were two factors increasing the risk of bushfire.
In addition to fires still burning from earlier ignitions, a number of significant new fires commenced in East Gippsland in December.
All of Victoria recorded accumulated Forest Fire Danger Index values for December in the highest 10 per cent of historical records, and the highest on record for December over the north and north west of the state and in East Gippsland.
The Forest Fire Danger Index is one common measure of fire weather conditions.
Rainfall influences the dryness of fuels and is a key factor in calculating indices for determining fire weather risk such as the Forest Fire Danger Index.
Dry soil conditions continued across much of Australia through December.
Month-to-date root zone soil moisture is close to lowest on record for much of East Gippsland and very much below average for the north east.
Rainfall deficiencies over the last three years are very deep - there are large areas of lowest on record rainfall over south east Australia due to the prolonged nature of the current dry period.
Rainfall has been below average in most months over much of the country since early 2017.
Consistent, widespread, above average rainfall over several months will be needed to lift areas out of deficiency.