Councils across the UK have been hard-hit by grit supply problems
A council says its grit bins are empty ahead of predicted severe snow as it has not received enough supplies since the last big freeze.
Torfaen council said it has just 110 tonnes in stock so would prioritise main routes only in the next few days.
It wants assurance from the Welsh Assembly Government that emergency salt deliveries will be made.
The Welsh Local Government Association said nearly all councils across the UK were in a similar position to Torfaen,
The Welsh Assembly Government said it was continually monitoring weather forecasts and salt stock levels and would prioritise resources "to ensure limited salt supplies are used in the most efficient and effective way".
Torfaen said its stocks had remained at critical levels since the prolonged cold snap over Christmas and the New Year but had now reached its lowest ever recorded level.
It said grit bins would remain empty until salt stocks were "substantially higher" and it was seeking immediate deliveries from Salt Cell, the national salt distributor based in Cheshire.
Executive member for operational services John Cunningham said: "With salt levels now perilous, drivers need to continue showing caution on the roads and just because they are black doesn't mean they're safe.
"Night time temperatures and road temperatures have remained regularly below freezing over recent weeks and only by treating main roads have we been able to carefully manage the pressure on our very low salt levels.
"We are concerned our grit barns will soon be empty unless we receive essential deliveries very quickly and are chasing the assembly government and Salt Cell for reassurances of deliveries in what is now a critical situation."
Severe snow warning
It said although orders for more grit were placed in December, because of the national shortage and continued snowfall around the country, only a few small deliveries had arrived over the last few weeks.
The Met Office has issued a warning of severe snow across most parts of Wales during Tuesday.
The Welsh Local Government Association (WLGA) said: "Even when there is no snow, when temperatures drop below zero (especially during the night) councils must send gritters out.
"Each run depletes their stock and in snow conditions they may be doing up to six runs a day.
"For a large council like Powys, 300 tonnes is used per treatment which could mean 1,800 tonnes in one day."
The daily demand on Salt Union was greater than the maximum daily supply of 6,000 tonnes, meaning no authority had been able to rebuild stocks during the prolonged cold spell, the WLGA added.
It said while there was a "hand to mouth" situation, cooperation between the WLGA and the assembly government meant supplies were getting to the most hard-pressed areas.
Councils are looking at options for increased storage which could be shared by neighbouring authorities, avoiding the problems caused "by all authorities converging on the Cheshire mine for supplies at times like these".