Heavy rain has been affecting several areas of Sumatra Island in Indonesia since around 11 October, causing flash floods and triggering landslides. Areas of Aceh, North and West Sumatra Provinces have all been affected. Around 20,000 people have been affected, with at least 20 fatalities reported and around 15 people missing.
North Sumatra
Heavy rain that hit areas in North Sumatra from 11 October, 2018 caused flash floods and landslides in several places.

One of the worst hit areas was Mandailing Natal Regency, North Sumatra, where 13 people died, including 11 students in Muara Saladi Village, Ulu Pungkut district, who died when their building was destroyed by flash floods on 12 October. A further 10 people are thought to be still missing. The incident occurred when the Aek Saladi River suddenly overflowed, pushing mud and debris onto the school building. At least 12 houses were washed away or completely destroyed.
Severe flooding of up to 2 metres deep was also reported in Natal and Muara Batang Gadis districts, and around 8 landslides in Batang Natal district.
Rain also caused landslides in several areas in the city of Sibolga, North Sumatra on 11 October where at least 4 people died in landslides and over 100 homes were severely damage by either flooding or landslides.

West Sumatra
Meanwhile at least 4 people have died in flash floods in North Lintau Buo District, Tanah Datar Regency in the province of West Sumatra. Three people are missing and 6 houses severely damaged..
Aceh
Disaster officials in Indonesia also reported flooding in Aceh province on the northwest tip of Sumatra Island. As of 16 October, 8,118 people were affected in 19 villages of Aceh Jaya Regency. Flooding struck after heavy rain over the last few days. No fatalities have been reported.
Social Media
Banjir landa 19 desa di 4 kecamatan di Kabupaten Aceh Jaya pada 16/10/2018 pukul 07.17 wib. Sebanyak 2.501 KK atau 8.118 jiwa terdampak banjir. Tidak ada korban jiwa. Dalam beberapa hari terakhir hujan deras melanda wilayah Aceh dan Sumut yang menyebabkan banjir dan longsor. pic.twitter.com/aMcib3ofhn
— Sutopo Purwo Nugroho (@Sutopo_PN) October 16, 2018
Inilah kondisi permukiman yang diterjang banjir bandang di Desa Muara Seladi Kec Ulu Pungkut Kab Mandailing Natal. Banjir bandang membawa lumpur, batu dan kayu gelondongan menerjang permukiman. Evakuasi terus dilakukan mencari korban. pic.twitter.com/D5UfPlWh3n
— Sutopo Purwo Nugroho (@Sutopo_PN) October 13, 2018
12 rumah hanyut dan rusak total, 9 rumah rusak berat, 3 fasum rusak berat akibat banjir bandang menerjang Desa Muara Saladi Kec. Ulu Pungkut Kab Mandailing Natal. Tim SAR dan masyarakat masih mencari 10 pelajar SDN 235 yang sekolah sore saat diterjang banjir bandang. pic.twitter.com/gfKyHWLUCH
— Sutopo Purwo Nugroho (@Sutopo_PN) October 13, 2018
Banjir dan longsor landa 4 wilayah yaitu di Kabupaten Mandailing Natal, Kota Sibolga, Kabupaten Tanah Datar dan Kabupaten Pasaman Barat selama 11-12/10/2018. Data sementara banjir dan longsor menyebabkan 20 orang meninggal dunia, 15 orang hilang dan puluhan orang luka-luka. pic.twitter.com/ROZswkn5Pq
— Sutopo Purwo Nugroho (@Sutopo_PN) October 13, 2018