Officials in the northeastern province of Badakhshan said snowfall had blocked access to Sheghnan, Kofab, Pamir, Raghistan and Kohistan districts where thousands of people require food aid and medical care.
Roads are the only means of accessing people as the country lacks a railway.
Snow, which usually starts falling in December in many areas, has also been reported in Daykundi, Baghlan and other northern and central provinces, according to the Afghanistan National Disasters Management Authority (ANDMA).
Medical and food aid deliveries to several vulnerable areas were impeded last winter due to blocked roads; over 2,000 people died - most of them children and the elderly - from cold-related diseases, ANDMA reported.
The government has promised to keep all roads open this winter.
Pre-positioning of aid
The government and aid agencies are worried that the early snow may scupper plans to pre-position food and non-food items in some areas.
"Of the 26,054 tonnes of food aid which has been promised by the government and aid organisations, so far only 5,476 tonnes have been delivered to Badakhshan," Mohammad Usman Abozar, an official at the provincial emergency response commission, told IRIN.
"We are very concerned about needy people in districts where access has been cut off by the snow," he said.
Similar concerns were echoed by provincial officials in Daykundi, Ghor and Faryab provinces.
"There are 17,420 most vulnerable households in Daykundi and to date only 2,613 tonnes of the expected 9,343 tonnes of food aid have been delivered," Bostan Saadiqi, head of the provincial department for rural rehabilitation and development, told IRIN.
The UN World Food Programme (WFP), which feeds about eight million food-insecure people in the country, has said it has been delivering food aid to areas where access could get tricky when winter sets in.
It has distributed 23,000 tonnes of wheat, oil, pulses and iodized salt to about 950,000 people in 23 provinces, and a further 36,000 tonnes would be distributed to 950,000 people in the coming months.
"So far 64 percent of the planned food has been dispatched," it said in a statement on 17 November.