Tuesday, 5 January 2010 - Monthly Climate Summary for Tasmania - Product code IDCKGC27R0
Tasmania in December 2009: A few very hot days after a cool startAfter 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.
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.
|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|
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
|Highest wind gust||144 km/h at Mount Wellington on
|Record highest December temperature|
in December 2009 (°C)
|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|
|Summary statistics for December 2009|
|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%|
|Launceston (Ti Tree Bend)||22.8||+0.4||31.7||29th||11.3||+0.7||6.2||25th||22.2||45.5||low||49%|
|Luncheon Hill (Forestry)||18.5||0.0||30.3||31st||8.8||+0.3||5.3||8th||82.0||93.5||low||88%|
|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%|
|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%|
|Fingal (Legge Street)||22.4||+1.0||34.4||31st||8.6||0.0||2.7||9th||27.4||49.6||average||55%|
|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%|
|St Helens Aerodrome||21.9||34.0||31st||11.8||7.9||9th||30.6|
|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%|
|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%|
|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%|
|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%|
|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%|
|Central Plateau (district 96)|
|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%|
|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%|
|Scotts Peak Dam||18.7||+0.4||34.4||31st||7.8||-0.1||3.2||20th||139.6||153.9||average||91%|
|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%|
|Antarctica and Macquarie Island (district 300)|
A Monthly Climate Summary is prepared to list the main features of the weather in Tasmania using the most timely and accurate information available on the date of publication; it will generally not be updated. Later information, including data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review, usually published in the fourth week of the month.
This statement has been prepared based on information available at 9 am on Tuesday 5 January 2010. Some checks have been made on the data, but it is possible that results will change as new information becomes available.
Averages are long-term means based on observations from
all available years of record, which vary widely from site to site.
They are not shown for sites with less than 10 years of record, as they cannot then be calculated reliably.
The median is sometimes more representative than the mean of long-term average rain.
The Rank indicates how rainfall this time compares with the climate record for the site,
based on the
(very low rainfall is in decile 1, low in decile 2 or 3,
average in decile 4 to 7, high in decile 8 or 9
and very high is in decile 10).
The Fraction of average shows how much rain has fallen this time as a percentage of the long-term mean.