Tuesday, March 01, 2011

Perth has hottest, driest summer on record ( BBC)

Perth has hottest, driest summer on record

The hot, dry conditions led to bushfires in February

Perth has had its hottest and driest summer on record. Just 0.2mm of rain fell from the beginning of December to the end of February, compared to the average of 32mm.

There were 59 days over 30 degrees centigrade, smashing the previous record of 53. There were also 15 consecutive nights where the minumum temperature did not fall below 20 degrees, breaking the previous record of 13 nights set in 1990. The average maximum temperature for the summer was a sweltering 32 degrees centigrade.

So why has Perth had such an extreme summer?

There has been a strong La NiƱa in the Pacific, which has led to the extreme rainfall in eastern Australia. This also tends to strengthen the easterly trade winds which blow hot dry air from the interior and reduce the number of weather systems moving in from the ocean, so western areas have been drier than usual.

Sea surface temperatures around western coasts have been 2-4 degrees higher than usual. In fact at the end of 2010 the sea surface temperatures reached record levels. This has kept the minimum temperatures at night high as the water has not been a cooling influence after the sun has gone.

The hot dry conditions led to bushfires in early February, destroying homes and businesses in the city.