Thursday, 5 January 2023 - Monthly Climate Summary for Western Australia - Product code IDCKGC11R0

Western Australia in December 2022: Wet in the north, dry in the south

December 2022 was warmer and wetter than average for Western Australia overall, and it was particularly wet for parts of the Gascoyne and Kimberley districts. Monthly rainfall totals were average to below average in the south and very much below average for the far south-west. Days were warmer than average across the Gascoyne and west Kimberley districts and cooler than average across the South East and South Coastal districts. December nights were warmer than average for Western Australia as a whole, and particularly warm in the inland eastern Pilbara.

Wet for the north, dry for the south

• For Western Australia as a whole, December rainfall was 26% above average.
• Rainfall in the top 10% of historical records for December was recorded for inland parts of the Gascoyne district and isolated parts of Kimberley. Below average to near average rainfall was observed for the south. Rainfall in the lowest 10% of historical records for December was observed for the South West district, although December is typically dry.
• In the first week of December, several cold fronts passed south of Western Australia, bringing isolated showers and high-based thunderstorms with little to no rainfall to the south. Storms on the 6th impacted harvesting. Isolated moderate daily rainfall for December was recorded in the South West Land Division on the 8th and 9th as a cold front passed. From the 20th to the 24th a low pressure trough brought severe thunderstorms and moderate to locally heavy rainfall to the southern Pilbara and inland Gascoyne and adjacent Central West. On the 20th, rainfall of 55 mm was recorded in one hour at Bullardoo. December daily record rainfall amounts were observed at Melangata with 51.2 mm on the 20th (previous record 35.6 mm on 23 December 2002 from 66 years of data) and at nearby Yarraquin with 42.0 mm on the 21st (previous record 40.0 mm on 5 December 2012 from 49 years of data).
• Tropical Cyclone Ellie developed in the Joseph Bonaparte Gulf on the 22nd and crossed the Northern Territory coast near Wadeye as a Category 1 cyclone late that night. On the 23rd the system was classed as a tropical low as it moved inland across the Gregory District of the Northern Territory. The tropical low moved into Western Australia on the 28th and re-connected with a strong monsoonal flow to the north, resulting in intensification over land as it tracked west. By the 30th widespread heavy to intense falls, flash flooding, riverine flooding, road closures, community isolation and peripheral severe thunderstorms were apparent around Fitzroy Crossing and Halls Creek. The Great Northern Highway was closed.
• Ex-tropical cyclone Ellie heralded the wettest December days on record in the Kimberley at Mount Amhurst with 101.0 mm on the 29th (previous record 94.0 mm on 17 December 1951 from 67 years of data) and at Gibb River with 138.6 mm (previous record 131.6 mm on 23 December 1987 from 100 years of data).
• Some sites had their highest December daily rainfall on record
• Some sites had their highest total December rainfall for at least 20 years

Mostly near average daytime temperatures

• The mean maximum temperature for Western Australia for December 2022 was 0.44 °C above the 1961-1990 average although it was the coolest since 2020.
• Daytime temperatures for December were around average for much of the state. Areas of very much above average temperature were recorded in the Gascoyne and west Kimberley districts, while an area of very much below average temperature was observed in the South East Coastal district.
• The mean minimum temperature for Western Australia for November 2022 was 0.39 °C above the 1961-1990 average, but it was the coolest since 2020.
• Severe to extreme heatwave conditions affected northern and interior Western Australia throughout the first week of December. By the 4th, daytime temperatures above 40 °C and overnight temperatures around 30 °C lead to extreme heatwave conditions in parts of the Pilbara, Kimberley, Interior north-east Gascoyne and northern Goldfields districts. On the 6th the Department of Health issued a Heatwave Watch and Act notice around the area of Marble Bar, and on the 7th, Heatwave Advice for the Kimberley. Heatwave conditions continued in until showers and thunderstorms arrived on the 14th. The hottest December day on record was recorded at Mandora with 48.5 °C on the 11th (previous record 48.4 °C on 22 December 1981 from 58 years of data).
• Extensive cloud cover, precipitation and cooler east to south-east winds lead to a cold outbreak in central Australia on the 16th, with the maximum temperature in the low 20s in and around Giles.
• Low intensity heatwave conditions developed again in the south-west Kimberley on the 18th as overnight minimum temperatures remained high. Low intensity heatwave conditions extended over western and southern parts of the state on the 22nd and were raised to severe heatwave over Eucla, Goldfields and Southern Interior on the 23rd.
• By the 27th heatwave warnings were current for the Pilbara, Gascoyne and Northern Interior districts. Cool conditions developed in the north due to the cloud coverage of ex-tropical cyclone Ellie from 28th to 31st.
• Some sites had their highest December temperature on record
• Some sites had their lowest December mean daily maximum temperature for at least 20 years
• Some sites had their lowest December temperature on record
• Some sites had their lowest December mean daily minimum temperature on record
• Some sites had their lowest December mean temperature on record
• Some sites had their lowest December mean temperature for at least 20 years

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

Click on a map to show it full size in a pop-up window

* 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 lower value has gone unreported

Extremes Maps Records Summaries Important notes the top

Extremes Maps Records Summaries Important notes the top