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When good rivers turn bad: Extreme flooding
Origins of bad weather

General Australian climate

Australian Flood Map - Click to enlarge
Source: Bureau of Meteorology
Tropical Cyclone Risk Areas - Click to enlarge
Source: Australian Severe Weather

The northern third of Australia lies in the tropics and so is warm or hot the year around. The rest of the country lies south of the tropics and has warm summers and mild or cool winters.

In winter, many parts of the south have occasional frosts. But the Australian Alps and the interior of Tasmania are the only areas of the country where temperatures remain below freezing for more than a day or so at a time.

Australia receives most of its moisture as rain. Snow falls only in Tasmania and the Australian Alps. About a third of the country is desert and receives less than 10 inches (25 centimeters) of rain a year. The deserts are too barren even for the grazing of livestock. Much of the rest of Australia has less than 20 inches (51 centimeters) of rainfall annually. Few crops can be grown in these regions without irrigation. The heaviest rainfall occurs along the north, east, southeast, and extreme southwest coasts.

The east coast of Queensland is the wettest part of the continent. Some places along this coast receive as much as 150 inches (381 centimeters) of rain a year. Parts of the southeast coast and of Tasmania are the only areas of the continent that receive uniform amounts of rainfall the year around. Rainfall is seasonal throughout the rest of Australia.

The Seasons

Australia lies south of the equator, and so its seasons are opposite those in the Northern Hemisphere. The southern part of the continent has four distinct seasons. Winter, the wettest and coolest season in Australia, lasts from June through August. Summer, which is the hottest and driest season, lasts from December through February.

Tropical northern Australia has only two seasons--a wet season and a dry one. The wet season corresponds with summer and lasts from November through April. The dry season corresponds with winter and lasts from May through October.

The wet season brings heavy downpours and violent storms, especially on Australia's north coast. In 1974, for example, a cyclone almost leveled the northern coastal city of Darwin. Floods plague many parts of Australia during the wet season. However, droughts are usually a far more serious problem. Nearly every section of Australia has a drought during the country's annual dry season.

Water conservation measures prevent these droughts from doing serious harm in most cases. However, Australia also has periods when little or no rain falls even during the wet season. These droughts can cause severe water shortages.

Next page

1. Origins of extreme weather | 2. Finding hidden treasure | 3. Streams and mass wasting
4. The Johnstone River, FNQ

The resources contained in this unit are courtesy of Earth Science Australia http://earthsci.org/