Lt Fazel Rahman, the police chief in the Guzirga i-Nur district of Baghlan province, said the death toll from Friday's flash flooding had climbed to 81 from 54.
He said 850 houses across several villages were completely destroyed and more than 1,000 were damaged by the heavy rain and flooding, leaving thousands of people in need of shelter, food, water and medicine.
Defence Ministry spokesman Gen Mohammad Zahir Azimi said Army helicopters were assisting in relief efforts in the remote district, which is just 140 kilometres north of the provincial capital Puli Khumri, but is an eight to nine hour journey by land because of the rugged terrain.
Rahman said local authorities had received around 100 tents, several hundred blankets and some food, but that more supplies were needed. Afghans living in the northern mountains have largely been spared from the country's decades of war, but are no strangers to natural disasters.
Last month, a landslide triggered by heavy rain buried large sections of a remote village in the northeastern Badakhshan province bordering China, displacing some 700 families.
Authorities have yet to provide an exact figure on the number of dead from the May 2 landslide, and estimates have ranged from 250 to 2,700.
Officials said it was impossible to dig up all the bodies. A landslide in Baghlan province in 2012 killed 71 people. After days of digging unearthed only five bodies, authorities gave up on the recovery effort and turned the area into a memorial.