A number of councils have been forced to preserve supplies of gritting salt
Drivers in the East are being urged to exercise caution and only travel if necessary as icy conditions create further problems on the roads.
Low temperatures have added to problems caused by heavy snow throughout the week, prompting police and councils to issue safety advice.
The Met Office has warned of further low temperatures overnight and the risk of ice on untreated surfaces.
Motorists are asked to adjust their driving to suit the conditions.
The Met Office said temperatures in the East could fall as low as -5C, with a hard frost developing.
Gritting crews were back out in force but a shortage of grit has forced some councils to focus on priority routes.
Essex County Council announced it was reducing the number of roads being gritted to preserve its supply of gritting salt.
In Cambridgeshire, police said further low temperatures were forecast.
Pc Tony Barrios, the county's casualty reduction officer, said: "Following the recent bad weather driving conditions have been far from ideal.
"With colder weather forecast for this weekend there is the potential for ice to cause problems."
In Hertfordshire, parents were asked to monitor conditions over the weekend and check with schools on Monday about possible closures.
A Hertfordshire County Council spokesman said: "Schools will seek to open Monday where conditions permit.
"Headteachers will be monitoring local weather forecasts carefully and will make a decision on whether to close a school based on local conditions.
"On Monday morning, parents can listen to their local radio station to find out if their school is closed.
"Many schools will update their own websites or answering machines with this information."
The council warned school bus services could be disrupted.
"Some services may not be able to get out, or reach normal pick up points where road conditions remain difficult," the spokesman said.
The council said it had enough salt "to keep Hertfordshire's roads safe for at least the next few days".