Severe Tropical Cyclone Namu was considered to be one of the worst tropical cyclones to impact the Solomon Islands on record, after it caused over 100 deaths within the island nations. It was first noted as a weak tropical depression to the north of the Solomon Islands during May 15, 1986. Over the next couple of days, the storm steadily intensified while meandering. After briefly moving west, the storm attained Category 2 intensity on the Australian intensity scale on May 18, as it moved through the island chain on the next day. Cyclone Namu attained peak intensity of . After retaining its peak intensity for a day, Namu turned south and weakened steadily. By May 21, the winds of Cyclone Namu had been reduced to only . Continuing to weaken, Namu turned east and dissipated on May 22, away from the island chain.
The system impacted the Solomon Islands, Vanuatu and New Caledonia and caused over 100 deaths, as well as varying amounts of damage to the island nations. As a result, the name Namu was later retired from the lists of tropical cyclone names for the South Pacific by the World Meteorological Organization.
The storm's slow motion allowed for prolonged periods of heavy rainfall, resulting in phenomenal flooding across the Solomon Islands. The islands of Malaita and Guadalcanal experienced the most significant damage from Namu. Coastal areas of the former were severely damaged by rough seas and strong winds, especially along the eastern side where entire villages were destroyed. Meanwhile, on the island of Guadalcanal, a village of 43 people had only 5 survivors. Moreover, Cyclone Namu flooded 75% of Guadalcanal's plains. In addition, 22% of homes were either damaged or destroyed on the island.
Across the Solomon Island group, schools, buildings, electricity, water supplies, roads, communication systems, forests, and agriculture sustained widespread damage. In some regions, nearly all homes were destroyed. Mudslides destroyed roads, bridges, water pipes and drainage systems. Crops such as cocoa, copra, coffee, and rice were destroyed. Villages throughout the entire island group sustained severe damage. Overall, approximately 90,000 people, one third of the country's population, were reported as homeless. In all, Cyclone Namu was responsible for at least 150 deaths, mostly from flooding and landslides. Property damage and economic losses across the Solomon Islands totaled $25 million and $100 million (1986 USD) respectively. During the aftermath of the storm, the government of the Solomon Islands declared a national state of emergency. Meanwhile, the United Kingdom, Papua New Guinea, the United States, and Japan also sent supplies and goods to the Solomon Islands.
Meteorological history
During the middle of May 1986, the monsoon trough of low pressure became very active, between the island nations of Tuvalu and the Solomon Islands. Two depressions subsequently developed within this monsoon trough, with the first going on to become Typhoon Lola in the Northern Hemisphere. The second depression developed within the Southern Hemisphere and was first noted by the Fiji Meteorological Service (FMS) during May 15, while it was located about to the north of Malaita in the Solomon Islands. During the next day, as the depression moved eastwards, it showed signs of weakening with clouds associated with the system disintegrating. However, the system remained in an area favourable for Tropical cyclogenesis, before the system re-intensified and developed two weak feeder bands. The United States Joint Typhoon Warning Center (JTWC) subsequently started to issue warnings on the system and designated it as Tropical Cyclone 33P early on May 17, after the depression had developed gale-force winds. During that day, the system moved south-westwards and acquired the characteristics of a tropical cyclone, before it was named Namu by the FMS, while it was located about to the north of Sikaiana.