One motorist died as more than 20 vehicles crashed across the county following freezing temperatures overnight.
There was widespread disruption in Sussex as people encountered black ice and flooding following days of heavy rain and a night when temperatures plummeted as low as -6C.
One person died when their Porsche crashed into a police car that was helping a broken-down vehicle on the A27 between Fontwell and Arundel.
Sussex Police said the driver died at the scene on Monday night.
The A27 was shut for crash investigation work.
A Sussex Police spokesman said: “The road remains closed in both directions while investigating officers continue their enquiries and ensure the road is safe for other vehicles.
“It is not yet known when the road will reopen.
“Anyone with information or dashcam footage which could assist officers with their investigation is asked to email it to collision.appeal@sussex.police.uk quoting Operation Burley.”
A three-vehicle smash closed part of the A27 near Worthing. The section at Hammerpot remained shut all day yesterday due to the risk of black ice which needed to be gritted.
The road closure caused traffic chaos in Clapham, Angmering and Goring as traffic was diverted.
Yesterday morning, a crash on the A27 at Selmeston caused queues that stretched back for miles to Polegate.
On the A259 at Friston, a car overturned and caused delays which led to Brighton and Hove Buses diverting via the A26 and A27.
The A23 at the Henfield turn-off was also closed due to black ice after a car came off the road.
There was another crash near the Denbigh pub in Bexhill at around 7.20am, as well as reports of a crash involving a car and motorbike on the A280 Angmering Bypass.
Two cars were involved in an accident in Old Crawley Road, near Crawley, at around 9.30am, although traffic was not affected.
Another accident caused delays in Storrington and there were crashes near Lower Beeding and Northlands Road, west of Crawley.
Motorists also had to contend with flooding in several areas, including the B2141 near Chichester, Barcombe Mills Road near Lewes, Denton Road in Newhaven, Golden Cross and near Bognor.
There was limited disruption to trains, although services from East Grinstead were halted following a landslip near the track.
A Network Rail spokesman said: “We're sorry but we've had to block the line between Hurst Green and East Grinstead as this landslip has been spotted on the London-bound side, affecting Southern Rail passengers.
“We hope this will be a temporary closure while we monitor the earth movement.
“We have people on site and specialists on their way to examine the slip further to judge whether we can reopen.”
A yellow weather warning, announced by the Met Office, comes in from 6pm tonight and will last until 12 noon tomorrow.
The national weather service has issued seven weather warnings across the country.
Temperatures are not expected to exceed 2C today, meaning ice will have little time to thaw in the day before freezing again.
The Highway Code urged people to drive in icy conditions only if the journey is essential.
It asked motorists to drive with care, even if the roads have been treated, and to keep well back from the road user in front as stopping distances can be ten times greater than on dry roads.
People should take care when overtaking vehicles spreading salt or other de-icer, particularly if they are riding a motorcycle or cycle.
They should watch out for snowploughs which may throw out snow on either side, be prepared for the road conditions to change over relatively short distances listen to travel bulletins and take note of variable message signs that may provide information about weather, road and traffic conditions ahead.
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