At least eight people fell prey to the biting cold in Uttar Pradesh, officials said Friday.
The deaths were reported from Varanasi, Ballia, Jaunpur, Bhadohi, Azamgarh and Ghazipur.
All schools up to class 8 were closed here Friday as the weather worsened over the last few days.
Lucknow District Magistrate Anurag Yadav said the schools would re-open Jan 15 only if the weather conditions improve.
The coldest place in the state was Unnao, near Lucknow, where the night temperature dropped to 3 degrees Celsius.
The maximum temperature in the state capital was 13.8 degrees Celsius, while the minimum was 6.2 degrees Celsius, which is one degree below normal.
At many places in the state, rain and hailstorm brought down the mercury.
At least five people died due to lightning in some parts of Uttar Pradesh, a home department official said.
Many trains were running hours behind schedule. Visibility on highways also came down to 300 metres. The official forecast similar weather this week.