Monday, 1st March 2004

MONTHLY CLIMATE SUMMARY - NSW REGIONAL OFFICE

NSW February 2004: Heatwave Conditions.

Overview: February in NSW can be described as one of the most intense heat waves ever encountered in the state in terms the length of time over which it occurred and the extent of area covered. A heat wave is simply defned as a period of more than a few days in a row of above average temperature for the particular location. The event was widespread and affected Queensland, New South Wales, Victoria and South Australia. 'At Wilcannia, NSW for example 16 days in a row were experienced where the maximum temperature was above 40 degrees from the 6th to the 21st of February previously 12 days, January 1979. The current spatial and temporal extent of this summer heat-wave places it amongst five of the most severe of the past century, alongside the events of January 2001, January 1982, December 1972 to January 1973 but falls short of January 1939 event (culminating in the so called 'Black Friday' the highest recorded temperatures ever in Adelaide on Thursday 12th January 1939, Melbourne on Friday 13th January 1939 and Sydney on Saturday, 14th Janurary 1939). The current heat wave was the stongest ever for February in NSW.

A substantial number of record temperatures for individual stations have been set in NSW this February. The highest February temperature ever was exceeded at Ivanhoe which reached 48.5 on 15th February. This is also the highest temperature in NSW in any month since 48.6 at White Cliffs on 3 January 1973.

February 2004 Rainfall: Most of this month's rain fell in late February on the eastern and northern parts of the State. For the month's total average conditions or better exist for approximately 80% of the State for February while the remainder of the State which includes an area near the entire length of the Victorian border is in the lowest 20% to 30% of rainfall figures for February. See Map 1

December 2003 to February 2004 Rainfall: The three month period from December to February is mostly average. Above average conditions exists in the northeast of the State mainly across the Northwest Slopes and Plains and parts of the Northern Tablelands. See Map 2

February 2004 Temperatures: The monthly mean maximum temperatures have been above average by 4 to 5 degrees in the worst affected areas which are parts of the Central Tablelands and Central West Slopes and also parts of the Lower Western District.The entire state is above average but most is between 2 to 4 degress above. See Map 3 The entire State's mean minimum temperatures are also above average mostly between 1 and 3 degrees. See Map 4

On an areal averaged basis NSW has recorded its highest ever maximum temperature for February in the last 55 years and the 2nd highest mean daily temperature for February (based on the average of the maximum and minimum) also in the last 55 years.

December 2003 to February 2004 Temperatures: The mean seasonal maximum temperature was 2 to 5°C above normal. with the quarter of the state northwest from about Orange fully 3-5°C higher for the 3 months. See Map 5.

Mean minimum summer temperature was 1-3°C above average. See Map 6.

A note about deciles: Deciles are used to give an element (in this case rainfall) a ranking. Deciles are calculated by arranging the totals in ascending order (from lowest to highest) then splitting them into 10 equal groups (thus the groups are called deciles). The first group would be in decile range one, the second group in decile range two, etc up to the highest annual totals (highest 10 per cent) being in decile range 10.

Further information:
A directory of Bureau services is available on poll fax: 1800 630 100
For the latest rainfall and temperature maps, see: http://www.bom.gov.au/climate/austmaps/