An amber weather warning has been put out by the Met Office for the south west, with snow expected in the early hours of tomorrow.
Weather experts are warning the area could expect more than 5-10cm of snow with the possibility of 15cm (6ins) in places.
Families living on high ground and in parts of the Cotswolds could see up to 25cm (10ins) of snow.
People have been warned they should be prepared to change their travel plans as there is potential for severe disruption, with the amber warning valid from 3am tomorrow until 9pm.
Snow is expected in the early hours of tomorrow, just in time for the morning rush hour. Widespread school closures are expected, with Rowdeford School, near Devizes already announcing it will not open because of the forecast.
Met Office spokesman Dan Williams said: "It is likely there will be some transport disruption and the advice would be for everyone to keep their eyes on local transport and travel updates and to check the weather forecasts. People must be prepared to change their plans."
South West Trains said the service between Bristol and Salisbury, which stops at Oldfield Park and Bath Spa Station, would not be running.
No South West trains would be running through Bath Spa , Bradford on Avon, Trowbridge, Warminster and Westbury stations.
A revised services would run on routes in Hampshire, Berkshire, Surrey, Dorset, Wiltshire, Somerset and Devon.
Meanwhile, Wiltshire Police are advising motorists to take care in respect of snowfall which is expected across the county from the early hours of tomorrow morning.
Chief Superintendent Paul Mills said: ‘The Met Office weather forecast predicts that we are likely to experience snow and icy roads throughout Wiltshire tomorrow and over the weekend. This will lead to poor driving conditions and motorists should take extra care.
"We are working closely with our partner agencies to ensure that there are sufficient resources to deal with any weather related incidents.
"Our best advice is to avoid any unnecessary journeys if at all possible however there are measures that all road users can take to help reduce any risks."
Advice for road users:
•Keep up-to-date with the weather forecast and road conditions before you set off on your journey
•Check that your vehicle is roadworthy. Make sure you have full visibility before driving, taking time to de-mist and de-ice all windows
•Use your lights When the roads are wet and icy, it can take twice as long to stop your vehicle so slow down
•Keep a safe distance from the vehicle in front In poor visibility be extra alert for hazards
•Carry warm waterproof clothing, a sleeping bag, food, water and a torch in your vehicle, in case weather conditions mean you have to stop
•Make sure you have plenty of fuel for your journey before you set off Use the highest gear possible to avoid wheel spin.
•Manoeuvre gently and avoid harsh braking and acceleration. If you start to skid, gently ease off the accelerator and avoid braking. If braking is necessary, pump the brakes, don't slam them on.
•Make sure your mobile phone is fully charged
•Poor weather conditions mean it can be harder for drivers to see pedestrians and cyclists, so be vigilant and make sure you can be seen however you are traveling and wear high visibility clothing.
Bosses at Great Western Hospital in Swindon say they will do all they can to keep disruption to services to a minimum during the severe weather conditions.
The hospital trust also runs the community hospitals in Chippenham, Trowbridge, Devizes, Savernake, Melksham and Warminster.
A GWH spokesman said patients with appointments and operations scheduled for tomorrow (Friday) should, if they can travel in safely, attend as normal unless the hospital contacts them.
The spokesman said contingency plans were in place to help essential staff get to the hospitals by using four-wheel drive transport.
The spokesman said it was too early to say if services will be affected but will be putting updates on its website – www.gwh.nhs.uk and Twitter - @GWH_NHS.
Trowbridge-based Wiltshire Farm Foods, which delivers frozen ready meals to elderly and disabled people in the county, said they were confident they would be able to cope with the adverse weather conditions forecast.
A spokesman for the company said: “We are taking each day as it comes but each van is equipped with shovels and other equipment to make sure we get through to customers.”
For all the latest weather news, see www.gazetteandherald.co.uk or www.wiltshiretimes.co.uk