Friday, 8 January 2021 - Monthly Climate Summary for New South Wales - Product code IDCKGC15R0

New South Wales in December 2020: wet across the state

Rainfall in December 2020 was above average across much of New South Wales, making it the wettest December since 2010 for the state as a whole. A slow-moving low pressure system in the middle of the month saw much of the northeast record their wettest December on record. Temperatures were generally milder than in recent year and overall, it was the coolest December since 2011.

Wet across the state

• Rainfall in December was above average across much of New South Wales, except for parts of the Riverina.
• For the state as whole, December rainfall was 81.8 mm, 63% above the 1961–1990 average and the wettest December since 2010.
• A slow-moving low pressure system in the middle of the month, and another trough on the 21st, resulted in much of the north-east area having its wettest December on record.
• Rainfall was more than twice the December average over much of New England and the Northwest Slopes, and over three times the December average along the north-east coast.
• The highest monthly total was 812.6 mm at Yarras (Mount Seaview) and many sites received over 600 mm.
• Many sites had their highest total December rainfall on record or their highest for at least 20 years.

Mild conditions

• Daytime temperatures across New South Wales were close to or below the December average.
• For the state as a whole, the December mean maximum temperature was 0.14 °C below average, making it the coolest December since 2011.
• Night-time temperatures were above average to very much above average in the north and along the coast, and below average in the south, particularly in the Riverina.
• For the state as a whole, the December mean minimum temperature was 0.69 °C above average, but after several very warm years nights were the coolest in December since 2013.
• The state-wide December mean temperature was 0.28 °C above average, making it the coolest December since 2011; in contrast December 2019 was 3.30 °C above average.
• Heatwave conditions at the start of the month saw a number of sites have their highest December temperature on record or their warmest December night on record.
• Brewon AWS, near Walgett, recorded 48.0 °C on the 1st, which is the second-highest temperature ever for December in New South Wales.
• An inland trough on the 21st resulted in several sites having their coldest December day on record.

Heavy rain in the north-east

• A slow-moving low pressure system and trough was near the coast in the New South Wales and Queensland border region from the 12th to the 17th.
• The system brought widespread heavy rain, damaging winds, abnormally high tides and dangerous surf to the north-east coastal area.
• Flash and riverine flooding was reported for the Tweed, Clarence, Richmond/Wilsons and Bellinger rivers.
• Damaging storm surges coincided with king tides, resulting in hazardous surf conditions and major coastal erosion at numerous beaches in the north-east, notably at Byron Bay.
• Daily totals over 200 mm were recorded at many sites over the 12th to the 17th, and sites had their highest December daily rainfall on record.
• Five-day totals of over 400 mm were recorded near the Queensland border, the highest such totals in the area since at least April 2017.

Extremes Maps Records Summaries Important notes the top

Extremes Maps Records Summaries Important notes the top

Maps
	Observed	Anomaly	Decile rank
Total rainfall
Mean daily maximum temperatures
Mean daily minimum temperatures

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* note: there are gaps in the historical record at this site, so it is possible a higher value has gone unreported

* note: there are gaps in the historical record at this site, so it is possible a higher value has gone unreported

Extremes Maps Records Summaries Important notes the top

Extremes Maps Records Summaries Important notes the top