Tropical Low 01U On 8 August, TCWC Perth started to monitor a tropical low located approximately to the west-northwest of the
Cocos Islands, on the
90th meridian east—the western edge of the BOM's area of responsibility. The tropical low moved in a west-southwesterly direction and a minimum barometric pressure of 1005 hPa (29.68 inHg). The storm moved out of the Australian region on the same day. By 06:00 UTC of 26 November, TCWC Jakarta began issuing advisories and was classified as a tropical depression. The JTWC, however, issued a
Tropical Cyclone Formation Alert early on 27 November, stating that satellite imagery depicted flaring convection near its center. Several hours later, TCWC Jakarta upgraded the system to a tropical cyclone, giving the name
Cempaka. Winds from the cyclone also blew ash from nearby
Mount Agung on Bali westwards to its popular beaches and far eastern
Java. On 30 November, Cempaka weakened into a tropical low, while turning to the southwest. TCWC Perth last mentioned Cempaka on 1 December. Although Cempaka never made landfall, the rainfall from the storm caused severe flooding and landslides across the southern half of Java and Bali, killing at least 41 people and destroying many homes and businesses.
Tropical Low 04U On 24 November, TCWC Darwin started to monitor a weak tropical low that had developed in the
Banda Sea. The system moved in a slow direction, and attained a minimum pressure of 1005 hPa, until it was last mentioned on 29 November.
Tropical Cyclone Dahlia Tropical Low 03U was first noted as a tropical depression by TCWC Jakarta on 24 November, while it was located about to the west of Jakarta, Indonesia. By 29 November, TCWC Jakarta upgraded the system to a tropical cyclone, receiving the name
Dahlia, making it the first time where at least two cyclones were formed and named by TCWC Jakarta in a single season. The JTWC followed suit the next day, designating the system as
01S. Best track reanalysis by the Bureau of Meteorology concluded that Dahlia reached tropical cyclone intensity as a Category 2, with sustained winds of 50 knots on 1 December and a minimum barometric pressure of 985 hPa. Dahlia maintained its intensity for several hours until the storm moved southeastwards and began to rapidly weaken on 2 December as it interacted with Ex-Tropical Cyclone Cempaka. Dahlia briefly reintensified for a period on 3 December. The BoM later issued its final bulletin on Dahlia early on 4 December. TCWC Perth last monitored on Dahlia on 5 December.
Tropical Cyclone Hilda During 26 December, the BoM reported that a tropical low had developed just off the
Kimberley coast, about to the north of
Derby. The system subsequently moved south-southwest parallel to the coast, as it developed further before it moved overland to the southwest of
Cape Leveque. On 06:00 UTC of 5 January, TCWC Perth began issuing advisories on the system, using the identifier
08U. TCWC Perth had recorded winds of , despite the fact that the system did not have the structure of a tropical cyclone. Three hours later, the JTWC followed suit and gave the system the designation
04S. TCWC Perth, however, discontinued advisories after Irving exited the basin on 12:00 UTC the same day.
Tropical Cyclone Joyce A tropical low developed over the
Joseph Bonaparte Gulf on 7 January 2018, and moved over the
Kimberley region of Western Australia the next day. On 10 January, the low moved offshore and began to develop, and the system was upgraded to a tropical cyclone, named Joyce, on 11 January. The system made landfall on the Western Australian coast the following day. The remnants of Cyclone Joyce bought heavy rain to the Perth Metro Area on 15 January; a total of of rain in 24 hours fell in
Perth, while
Rottnest Island recorded the highest amount of rain in the metro, which was a total of .
Tropical Low 11U The slow-moving system brought copious rains to a broad swath of coastal Australia. In
Kimberley, Western Australia, near-record rainfall accumulations of in four days caused extensive flooding. In a 24-hour span, of rain fell across
Broome, Western Australia, with flood waters in some areas reaching depths of . Portions of the
Great Northern Highway and Cape Leveque road were closed. Coastal areas experienced powerful winds reaching with gusts to ; these winds downed many trees and power lines. The effects of the low were considered substantially worse than Hilda and Joyce, tropical cyclones that affected the same region earlier in the season.
Severe Tropical Cyclone Kelvin Tropical Cyclone Kelvin formed on 12 February and rapidly intensified into a Category 2 Storm (Australian Scale) and a Category 1 Storm (Saffir–Simpson) Kelvin made landfall, but unusually formed an eye over land. Kelvin sustained cyclone or hurricane intensity until dissipating on 20 February. Tropical Cyclone Kelvin brought widespread heavy rainfall to the
Kimberley region which had already been saturated by other tropical cyclone systems. As a result, significant flooding occurred in parts of the Kimberley, including in the towns of Broome and
Bidyadanga. Property damage was sustained at Broome and
Anna Plains Station, where the cyclone made landfall, as well as infrastructural damage to the
Great Northern Highway as a result of the heavy rainfall and flooding.
Tropical Cyclone Linda