Tuesday, 5 January 2010 - Monthly Climate Summary for Tasmania - Product code IDCKGC27R0

Tasmania in December 2009: A few very hot days after a cool start

After a generally cool month temperatures warmed in the final week, peaking on the 31st with many sites reaching into the mid to high 30s. On the evening of New Years Eve, Hobart was the warmest of all Australian capital cities and a spectacular lightning show ended the year. For the whole month it was wetter than usual in the west and parts of the east and southeast, but the remainder of the state was drier than usual.

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A hot end to the year

A warm airmass ahead of an approaching cold front on the 31st made it the warmest day of the month, and for some sites, the year. Hobart reached 38.3 °C and Bushy Park 38.4 °C; there have only been 3 previous occurrences of December temperatures this high in Tasmania (the December record is 39.2 °C at Hobart Airport in 1998). A few sites in the south had their hottest December day on record. Temperatures stayed high right into the evening; it was still 30.7 °C in Hobart at 9 pm, easily the highest 9 pm New Year's Eve temperature ever recorded in the city and (for a few hours at least) making Hobart the warmest capital city in Australia. During the evening, a line of thunderstorms moved across the state giving a spectacular show of lightning, particularly in the southeast. Lightning strikes started several fires, mainly in the south.

Warm overall after a cool start

Daytime temperatures were mostly cooler than usual in the first three weeks, but a warm finish ensured mean maxima for the month were around a degree above average in the east and half a degree above average elsewhere. The 31st was the hottest day of the month for most sites but the 16th was also hot with a strong northerly airflow pushing temperatures over 30 °C in most areas. In stark contrast, on the 17th temperatures struggled to reach 15 °C in the west, south and east. The change was dramatic: very high to severe fire dangers on one day were replaced by rain and some snow on the higher peaks the next. Although large temperature changes are common with summertime cold fronts, this particular change was very marked. Several sites were 20 °C cooler after the change: Campania fell from 36.3 °C (the warmest in the state) on the 16th to 13.8 °C on the 17th, and Hobart fell from 34.0 °C (its second-hottest day of the year) to just 12.4 °C (its coldest December day since 1992). The last time there was such a large fall in Hobart's temperature from one day to the next was in December 1945.

Some warm nights

Cool and warm nights were interspersed but averaged over the whole month minimum temperatures were mostly within half a degree of normal. There were three especially warm nights (the 17th, 24th and 31st) when minima were generally at least 5 degrees warmer than usual and a number of sites had their warmest December night since the early 2000s. Flinders Island had the warmest nights; after hovering near 27 °C for most of the night on the 17th before the temperature cooled slightly after 5 am to a low of 20.5 °C. It also didn't fall below 18 °C on the 24th and 31st. The coldest night was -2.4 °C at Liawenee on the 14th.

Some heavy rain but mostly drier than usual

Because winds were mostly westerly and several cold fronts crossed the state, most of the rain in December fell in the west. It rained in the west nearly every day for the first two weeks, and all of the highest daily totals were at Mount Read: 77 mm on the 12th, 55 mm on the 19th and 45 mm on the 10th. Rainfall extended statewide on the 3rd, 10th and 17th as weak low pressure systems formed on fronts crossing the state, and with a front on the 24th. There were some good falls in the east: on the 10th many parts received 10 to 20 mm and on the 17th falls of 25 to 40 mm were widespread. Of Hobart's 57 mm for the month, 32 mm fell on the 17th. The total is just slightly above the long-term average for December. For the whole month it was drier than usual in most areas except for the west coast and parts of the east and southeast. The wettest overall was 378.0 mm at Mount Read, whilst there was only 18.4 mm at Devonport Airport.

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Extremes in December 2009
Hottest day	38.4 °C at Bushy Park on the 31st
Warmest days on average	23.3 °C at Bushy Park and Campania
Coolest days on average	11.7 °C at Mount Read
Coldest day	5.5 °C at Mount Read on the 4th
Coldest night	-2.4 °C at Liawenee on the 14th
Coolest nights on average	3.3 °C at Mount Wellington
Warmest nights on average	13.6 °C at Swan Island
Warmest night	20.5 °C at Flinders Island Airport on the 17th
Wettest overall	378.0 mm at Mount Read
Driest overall	18.4 mm at Devonport Airport
Wettest day	77.2 mm at Mount Read on the 12th
Highest wind gust	144 km/h at Mount Wellington on the 18th

Details Extremes Records Summaries Important notes the top

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Record highest December temperature
	Highest temperature in December 2009 (°C)		Previous highest for December		Years of record	Average for December
Cape Bruny Lighthouse	35.2	on the 31st	34.2	on the 12th in 1994	53	16.9
Mount Wellington	27.6	on the 31st	27.5	on the 11th in 1998	28	10.9
Geeveston (Cemetery Road)	37.0	on the 31st	36.6	on the 6th in 1994	24	19.9
Dover	37.3	on the 31st	36.1	on the 6th in 1994	20	19.0

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Summary statistics for December 2009
	Maximum temperatures for December (°C)				Minimum temperatures for December (°C)				Rainfall for December (millimetres)
	Mean for December 2009	Diff from average	Highest for December 2009		Mean for December 2009	Diff from average	Lowest for December 2009		Total for December 2009	Average for December	Rank of December 2009	Fraction of December average
Northern (district 91)
Bridport (Sea View Villas)	20.2	+0.1	26.0	31st	10.6	-0.5	1.5	30th	33.0	43.8	average	75%
Burnie (Round Hill)	20.1	+0.7	28.7	29th	12.0	+0.9	7.2	11th	20.4	62.9	low	32%
Cape Grim BAPS	17.7	+0.5	27.0	31st	12.0	+0.2	9.0	11th	40.0	45.7	average	88%
Cressy Research Station	23.2	+0.4	32.6	31st	8.8	+0.5	1.8	25th	26.8	42.4	average	63%
Devonport Airport	20.0	+0.5	27.2	29th	10.6	+0.1	4.9	9th	18.4	52.8	low	35%
Launceston (Ti Tree Bend)	22.8	+0.4	31.7	29th	11.3	+0.7	6.2	25th	22.2	45.5	low	49%
Launceston Airport	22.5		31.0	31st	9.1		3.8	9th	23.4
Low Head	18.8	0.0	21.6	31st	13.1	+0.4	10.0	1st	22.8	43.1	average	53%
Luncheon Hill (Forestry)	18.5	0.0	30.3	31st	8.8	+0.3	5.3	8th	82.0	93.5	low	88%
Marrawah	18.5	+0.2	28.8	31st	11.0	+0.4	7.2	20th	46.2	64.2	average	72%
Scottsdale (West Minstone Road)	21.3	+0.5	30.7	31st	9.4	+0.2	3.9	25th	35.2	67.1	low	52%
Sheffield School Farm	19.6	+0.1	29.6	29th	8.8	-0.1	4.0	9th	36.2	59.6	average	61%
Smithton Aerodrome	19.8	+0.4	26.8	31st	9.1	-0.5	3.6	21st	35.4	60.8	low	58%
Wynyard Airport	20.3	+0.9	28.7	29th	9.6	+0.1	3.3	9th	22.6	63.2	low	36%
East Coast (district 92)
Bicheno (Council Depot)	21.3	+1.3	32.7	31st	12.3	+0.8	8.3	18th	56.7	68.6	average	83%
Eddystone Point	21.8	+2.5	27.1	29th	12.4	+0.2	7.8	9th	23.4	59.8	low	39%
Fingal (Legge Street)	22.4	+1.0	34.4	31st	8.6	0.0	2.7	9th	27.4	49.6	average	55%
Friendly Beaches	22.0	+0.2	35.3	16th	12.0	+0.4	6.9	18th	50.4	37.9	high	133%
Lake Leake (Elizabeth River)	18.7	+1.2	29.3	31st	7.3	+0.4	2.4	25th	57.8	72.9	average	79%
Maria Island (Point Lesueur)	20.2		30.2	16th	12.1		9.0	18th	57.2
Orford (Aubin Court)	21.4	+1.0	34.8	31st	11.3	+0.8	6.8	18th	74.0	64.1	average	115%
Scamander	21.3	+1.0	35.1	31st	11.9	+0.6	8.4	18th	34.0	61.5	average	55%
St Helens Aerodrome	21.9		34.0	31st	11.8		7.9	9th	30.6
Swan Island	19.9		28.4	31st	13.6		10.1	1st	25.6
Swansea Post Office	22.0	+1.4	35.3	31st	10.7	+0.2	6.2	18th	58.6	59.9	average	98%
Midlands (district 93)
Ross (The Boulevards)	23.0	+0.4	32.9	31st	9.3	+0.8	3.3	25th	45.0	38.2	average	118%
Southeast (district 94)
Bull Bay (Lauriston)	20.6	+0.8	37.2	31st	10.9	+0.3	6.9	18th	48.2	62.9	average	77%
Campania (Kincora)	23.3		38.1	31st	10.0		5.1	2nd	55.6	36.6	high	152%
Cape Bruny (Cape Bruny)	19.3	+1.2	36.1	31st	10.6	0.0	7.6	20th	36.0	59.4	low	61%
Cape Bruny Lighthouse	18.7	+1.8	35.2	31st	10.7	+0.4	5.6	12th	43.0	76.7	low	56%
Dover	20.1	+1.1	37.3	31st	8.7	-0.2	2.9	20th	33.0	71.9	low	46%
Geeveston (Cemetery Road)	20.8	+0.9	37.0	31st	9.0	+0.4	3.5	20th	48.0	71.7	average	67%
Grove (Research Station)	21.3		37.1	31st	8.0		2.8	15th	55.6
Hobart (Ellerslie Road)	21.9	+1.6	38.3	31st	11.4	+0.6	8.0	18th	57.2	56.9	average	101%
Hobart Airport	21.8	+1.2	37.1	31st	11.3	+0.6	7.4	18th	54.4	53.7	average	101%
Maatsuyker Island Lighthouse	16.4	+0.7	30.4	31st	10.4	+0.8	8.2	4th	95.4	90.4	average	106%
Melton Mowbray (North Stockman)	22.0	+0.2	36.2	31st	8.8	-0.2	3.2	14th	39.2	37.9	average	103%
Mount Wellington	12.8	+1.9	27.6	31st	3.3	+0.5	-0.9	4th	63.0	87.7	average	72%
Tasman Island	17.1		31.1	31st	9.8		7.1	8th	68.2
Tunnack Fire Station	19.3	-0.3	30.1	31st	7.6	+0.2	1.5	14th	38.4	51.0	low	75%
Derwent Valley (district 95)
Bushy Park (Bushy Park Estates)	23.3	+1.3	38.4	31st	8.7	-0.4	4.4	15th	27.6	50.6	low	55%
Maydena Post Office	19.8	+0.1	35.2	31st	7.4	0.0	2.6	20th	71.5	88.6	average	81%
Ouse Fire Station	23.2	+0.2	37.3	31st	8.5	-0.1	2.2	14th	21.6	35.7	average	61%
Tarraleah Village	18.6	+0.9	32.1	31st	6.0	-0.1	1.9	8th	50.1	91.4	low	55%
Central Plateau (district 96)
Butlers Gorge	17.2	+0.6	31.0	31st	4.7	-0.8	-0.8	8th	99.6	127.0	average	78%
Lake St Clair National Park	17.5	+0.3	31.0	31st	4.3	-0.7	-1.0	1st	116.2	133.7	average	87%
Liawenee	16.9		28.0	16th	3.7		-2.4	14th	33.0	65.0	low	51%
West Coast (district 97)
Hartz Mountain (Keoghs Pimple)	14.6	-0.2	30.9	31st	5.2	+0.2	1.3	4th	80.4	81.0	average	99%
Mount Read	11.7	+0.1	25.0	31st	3.8	0.0	-0.5	4th	378.0	292.4	high	129%
Scotts Peak Dam	18.7	+0.4	34.4	31st	7.8	-0.1	3.2	20th	139.6	153.9	average	91%
Strahan Aerodrome	19.3	-0.4	34.5	31st	9.8	+0.2	4.6	20th	123.4	79.9	high	154%
Strathgordon Village	17.0	-0.2	29.0	30th	7.6	-0.7	4.0	20th	250.7	202.4	high	124%
Warra	17.3		33.1	31st	6.6		1.1	20th	118.4
King Island (district 98)
King Island Airport	19.8	+1.3	35.2	31st	10.9	0.0	5.6	26th	33.6	50.6	average	66%
Flinders Island (district 99)
Flinders Island Airport	21.1	+1.0	34.6	16th	11.9	+0.1	4.9	21st	28.8	58.1	low	50%
Hogan Island	20.7		33.8	31st	13.1		10.0	11th	38.6
Antarctica and Macquarie Island (district 300)
Macquarie Island	8.2	+0.3	9.7	24th	4.2	-0.1	1.3	14th	67.0	77.2	average	87%

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