The eighth named storm of the 2008–09 Australian region cyclone season, Hamish developed out of an area of low pressure on 4 March near the Cape York Peninsula.

Deep convection developed around the eye, fueling further intensification, which allowed the storm to become a Category 5 tropical cyclone late on 7 March.

[2] On the following day, the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert as convection wrapped around the centre of circulation and an anticyclone developed over the system, allowing for good outflow.

[3] Hours later, the BoM classified the low as Tropical Cyclone Hamish as the storm began to moved southward in response to a mid-level ridge situated to the east.

A steady south-easterly track was fully established by this time as the ridge to the east and a trough over central Australia prevented westward movement.

[1][9] At the same time, the JTWC assessed the storm to have nearly become a Category 5 equivalent on the Saffir–Simpson Hurricane Scale; peak one-minute sustained winds were estimated at 250 km/h (160 mph).

[11] After maintaining Category 5 status for roughly 24 hours,[1] Hamish began to weaken as the interaction with coastal Australia and increased wind shear took their toll.

[12] Late on 8 March, an eyewall replacement cycle had begun to take shape,[13] allowing the storm to maintain Category 4 intensity for the following few days.

[1] By 10 March, the storm finally began to show signs of steady weakening as shear continued to increase due to an approaching trough from the west.

Substantial loss of convection took place during this time,[15] causing Hamish to weaken below severe tropical cyclone status by 11 March.

[19] Early the next morning, a Cyclone Warning was declared for areas between Cape Melville and Cardwell and the watch was extended to Hayman Island[20] and later to Mackay[21] and St Lawrence.

[23] Due to heavy rains produced by the outer bands of the cyclone, Flood Warnings were issued for areas between Cooktown and Townsville.

[24] On 7 March, Queensland Premier Anna Bligh signed a Declaration of Disaster Situation which permitted Australian officials to evacuate residents from the areas most at risk from Cyclone Hamish.

The Golden Beach Progress Association chairman, Mick Graham, feared that if this happened, the structure of the island and passage would change.

[41] On the Discovery Coast, constant beach erosion washed away numerous trees and some walkways, with officials estimating that millions of tonnes of debris were in the water.

The Environmental Protection Agency stated that it was possible for light vehicles to continue along the normal route during low tide but were recommended to take the two-hour detour.

[46] Along the storm's 500 km (310 mi) track parallel to the Queensland coastline, the eye passed over a substantial portion of the Great Barrier Reef, resulting in some of the worst damage to the area in recent history.

The Bureau of Meteorology estimated that about a quarter of the area was impacted by the storm, with some parts being within 30 km (19 mi) of Hamish's eye when it was a Category 5 cyclone.

[48] Due to the severity of the damage, the Queensland Seafood Industry Association requested that the reef be declared a disaster zone between Bowen and Wide Bay.

"[49] A 183 m (600 ft) cargo ship called the MV Pacific Adventurer was carrying 60 containers of ammonium nitrate when it encountered rough seas produced by Hamish, while located about 13 km (8.1 mi) east of Cape Moreton.

[51] Around 3:15 a.m. EST on 11 March 31 of the containers spilled into the sea along with a large amount of heavy fuel, causing the surface of the water to become slick.

The coverage and depth of the spill led Anna Bligh to state that the crew members of the ship were likely understating the amount of fuel that leaked out.

[58][59] Health officials hoped that rains from Hamish would help to reduce an ongoing dengue fever outbreak; however, little rainfall reached the coast, allowing further growth of the disease.

[63] Following the oil spill, Queensland Premier Anna Bligh declared two islands and parts of the Sunshine coast as disaster areas.