Snow has continued to cause disruption across Tyneside
Almost 300 schools remain closed across Northumberland and Tyneside because of the freezing conditions.
More than 150 schools in Northumberland alone say they are staying shut as temperatures reached -16C (3.2F) in the Otterburn area.
Councils are warning that supplies of grit are running low, with Newcastle and Gateshead saying supplies are down to just a few days.
Commuters faced continued delays on roads, trains and at airports.
A spokesman for Gateshead Council said: "We have reserves of approximately 1,700 tonnes at present, this is enough to cope with up to three days of snow and freezing conditions.
"Measures are being put in place to use the remaining stocks as economically as possible and to ensure that we can continue to keep the major routes into and around Gateshead safe."
A Newcastle City Council spokesman added: "We have enough grit to last us until next Monday when we expect a further delivery. This is dependent on the current forecast proving to be accurate.
"To make our current grit supplies go further we are mixing it with a chippings substance which when mixed with grit helps clear the snow.
"We have sourced 1,000 tonnes of this and received some of it on Friday."
Northumberland County Council said it had enough grit to last up to six days.
Police and the Highways Agency have urged motorists to use extreme care on roads which have become treacherous due to ice.
Most major road routes are passable with care.
Rail services in the East Coast Mainline and those to Carlsile and the North West were subject to delays.
Northern Rail services between Newcastle and Chathill in Northumberland were suspended earlier due to the poor weather conditions.
Newcastle Airport remains open, but passengers are urged to check timetables before travelling.