Thunderstorms and heavy rainfall are forecasted to occur starting from 01 January 2026, 02:00 WIB in parts of Sumatera Utara especially in: Adian Koting, Aek Songsongan, Andam Dewi, Angkola Barat, Angkola Sangkunur, Angkola Selatan, Arse, Bahorok, Baktiraja, Balige, Bangun Purba, Barus, Barus Utara, Barusjahe, Batang Angkola, Batang Serangan, Batang Toru, Berampu, Berastagi, Besitang, Binjai, Binjai Barat, Binjai Kota, Binjai Selatan, Binjai Timur, Bintang Bayu, Deli Tua, Dolat Rayat, Dolok Panribuan, Dolok Sanggul, Dolok Silau, Galang, Garoga, Gebang, Gunung Meriah, Gunung Sitember, Habinsaran, Hamparan Perak, Harian, Jorlang Hataran, Juhar, Kabanjahe, Kerajaan, Kolang, Kuala, Kutabuluh, Kutalimbaru, Kutambaru, Lae Parira, Laguboti, Laubaleng, Lintong Nihuta, Manduamas, Mardingding, Medan Baru, Medan Helvetia, Medan Johor, Medan Maimun, Medan Polonia, Medan Selayang, Medan Sunggal, Medan Tuntungan, Merdeka, Merek, Muara, Muara Batang Gadis, Muara Batang Toru, Munte, Nainggolan, Naman Teran, Namorambe, Natal, Onan Ganjang, Onan Runggu, Padang Tualang, Pagaran, Pagindar, Pahae Jae, Pahae Julu, Pakkat, Palipi, Pamatang Silima Huta, Pancur Batu, Pangaribuan, Pangururan, Paranginan, Parbuluan, Parlilitan, Parmonangan, Patumbak, Payung, Pegagan Hilir, Pematang Jaya, Pergetteng Getteng Sengkut, Pintu Pohan Meranti, Pollung, Purba, Raya Kahean, Ronggur Nihuta, Saipar Dolok Hole, Salak, Salapian, Sawit Seberang, Sei Bingei, Sei Lepan, Selesai, Serba Jadi, Sianjar Mula Mula, Siantar, Siatas Barita, Sibiru-Biru, Sibolangit, Siborong-Borong, Siempat Nempu, Siempat Nempu Hilir, Siempat Nempu Hulu, Siempat Rube, Sijamapolang, Silahisabungan, Silima Pungga Pungga, Silinda, Silou Kahean, Simangumban, Simpang Empat, Sipahutar, Sipoholon, Sirandorung, Sirapit, Sitelu Tali Urang Jehe, Sitelu Tali Urang Julu, Sitinjo, Sitio-Tio, Sorkam Barat, Sosor Gadong, Stabat, Stm Hilir, Stm Hulu, Suka Bangun, Sumbul, Sunggal, Tampahan, Tanah Jawa, Tanah Pinem, Tapian Nauli, Tarabintang, Tarutung, Tigabinanga, Tigalingga, Tiganderket, Tigapanah, Tinada, Wampu. These conditions may lead to reduced visibility, strong winds, and localized flooding. The public is strongly advised to remain vigilant during this period, limit outdoor activities, and take all necessary precautions to ensure safety. Conditions are expected to gradually improve by 01 January 2026, 05:00 WIB.