Kathmandu experienced the coldest weather in years on Sunday with the mercury falling to zero degrees Celsius.

According to the Meteorological Forecasting Division (MFD), temperature in Kathmandu Valley has plummeted in the past week. Zero degrees temperature was last recorded in Kathmandu in 2015.

This makes Sunday the coldest day in the Capital in three years, according to Min Kumar Aryal, a meteorologist with the MFD. The constant drop in temperatures over the past few days is normal for this time of the year, he said.

Weatherman call the chilly condition a “jet streams phenomenon”, resulting from fast moving air currents in the atmosphere nearly 15km above the earth’s surface.

The sharp drop in mercury in Kathmandu and around the country is due to the atmospheric conditions, according to Aryal. “Jet streams are right above Nepal at present while active radiant cooling system and light wind on the ground are keeping temperatures low,” added Aryal.

A north-westerly wind passing through the Himalayas has also pushed temperatures down. Temperatures in Kathmandu had hit zero degrees also in 2012 and 2006. In 1970, temperatures had dipped 3 degrees below zero, according to the MFD.

On Sunday, Jumla, Jomsom and Jiri measured minimum temperatures of minus 8.7, minus 5 and minus 4 degrees Celsius, respectively, followed by Dang (0.5), Dipayal (0.6), Birendranagar (0.9) and Taplejung (1.5), among the places that experienced one of the coldest days.

While the chill grows across Tarai, thick fog has affected people’s mobility along with vehicular movement.