Located on the western tip of the Pilbara coast, the most cyclone-prone part of Australia’s coast, Exmouth has felt the full force of one of the strongest cyclones in Australia’s history. In March 1999 tropical cyclone Vance moved down Exmouth Gulf causing winds recorded to 267 km/h, the highest ever wind gust measured on the Australian mainland

It is difficult to compare historical cyclones prior to Exmouth being developed in the 1960s. The pearling fleet from Port Hedland regularly visited Exmouth Gulf in the late 1800s and in December 1875 a cyclone devastated the fleet sinking several boats and claiming 59 lives. Pastoral stations and then the Cape Vlamingh lighthouse (1911) provided some details of cyclones during the early years. The first recorded major cyclone impact was in February 1945 when the three-year old naval base was extensively damaged and troops were withdrawn.

Overall it is estimated that a cyclone impact causing wind gusts in excess of 90 km/h in the vicinity of Exmouth occurs about once every two to three years on average. However, the frequency is not evenly distributed. Since 1982 there have only been three cyclones causing gales, including Vance, but there were fourteen cyclones in the previous twenty years. Although the inadequacy of early wind records make it difficult to compare events, it is estimated that there have been four severe cyclones causing winds of at least 170 km/h since 1910: 1945, 1953, 1964 (Katie) and 1999 (Vance).

Along the central Pilbara coast the cyclone season runs from mid December to April peaking in February and March as shown in the graph of monthly occurrence.

The development of the offshore oil and gas industries, and more recently, the tourism industry has increased the damage potential of cyclones in the region. Substantial economic losses can be incurred even with the threat of a cyclone impact owing to lost production or disruptions to shipping activities. Fortunately modern structures are built according to cyclone wind ratings and are far less susceptible to damaging winds than those constructed in earlier times.

By not being on a major river, Exmouth is not at risk of major flooding caused by rainfall alone. Localised flooding is certainly possible in susceptible areas especially near creeks and low-lying areas. The road link to the south is particularly vulnerable to being cut-off for a period following heavy rain. Major flooding in Exmouth is typically associated with storm surge, as discussed in the next section.

The heaviest rainfall is not necessarily associated with the most intense cyclones but rather with the cyclone’s track, speed and areal extent. A tropical cyclone in 1918 caused 377.1 mm over two days at Exmouth Gulf station. Cyclone Rita in 1971 produced 226.6 mm of rain at Learmonth and 194.8 mm at Exmouth. Wind damage was minimal in both of these events.

Storm surge is a major threat around Exmouth Gulf. Storm surge is a complex function of cyclone intensity and motion, extent of maximum winds, bathymetry and coastline shape. The actual water level, called the storm tide is a combination of the storm surge and tidal variation. The worst case scenario is to have a severe cyclone pass near the town at the time of high tide, in which case the water level will be many metres above the highest astronomical tide. Given the significant tidal variations in the region, this is a rare occurrence. Even with an intense cyclone the highest surge is typically restricted to less than 80 km of the coast owing to the nature of the extent of a cyclone’s maximum winds.

Millions of lives were changed by the record-setting 2005 Atlantic hurricane season – a “worst case scenario” for the United States. The 27 named tropical storms beat the old record of 21 in 1933. Five hurricanes (Dennis, Katrina, Ophelia, Rita and Wilma) and three tropical storms (Arlene, Cindy and Tammy) directly impacted the country: destroying lives, demolishing homes and wrecking the landscape. More than a thousand people lost their lives and many more were left battered, broken, displaced or homeless. Entire neighborhoods were wiped out by the combination of strong winds, heavy rain, storm surge and floodwaters.

While an active hurricane season was anticipated by meteorologists and experts at the National Hurricane Center, the destruction and sheer number of storms was simply overwhelming. Many residents, particularly in the southeastern U.S., were under a state of alert that lasted for months. As early as late July, more than a month before the peak of the season, seven storms had already formed, including two Category 4 storms that formed in rapid succession (Hurricanes Dennis and Emily). Typically the waters of the Gulf of Mexico are too cool at that point in the season to support such storms. However in 2005, warmer-than-normal sea surface temperatures combined with paths over very warm ocean currents which enabled many storms to rapidly intensify.

By season’s end, 14 hurricanes had formed, beating the previous record of 12 in 1969. 2005 also had the most Category 5 storms with three (Katrina, Rita, and Wilma). Seven storms were major hurricanes-category 3 or higher-of which a record four hit the United States (Dennis, Katrina, Rita, and Wilma). And, for the first time since the current hurricane naming system was introduced in 1953, all 21 names on the list were exhausted, forcing the National Hurricane Center to name six late storms after Greek letters. An average season typically has only 11 named storms, including six hurricanes.