Why does rainfall decrease from Queensland’s coast toward the interior?

The decrease in rainfall from Queensland’s coast toward the interior is primarily due to the presence of the Great Dividing Range, a series of plateaus and mountains that parallels the coast.1

As moisture-laden winds from the ocean move inland, they encounter these highlands and are forced upward. This process causes the air to cool and release its moisture as orographic precipitation on the windward, coastal side of the range. By the time the air masses descend on the western side of the mountains, they have lost much of their moisture, leaving the interior in a rain shadow where precipitation levels are significantly lower. Consequently, while coastal zones may receive up to 180 inches (4,575 mm) of rain annually, totals in the southwest interior can drop to as little as 5 to 6 inches (125 to 150 mm).234