Severe flooding has closed the A29 in Pulborough this morning (Friday January 3).
London Road has been shut in both directions between the A283 Station Road junction and the Old London Road junction, because of flooding.
West Sussex County Council said the situation could be prolonged as more bad weather is forecasted.
A spokesperson said: “We understand the inconvenience caused by flooding on the A29 but currently there is nowhere to discharge the floodwater to and until this changes we can take no further action.
“The surrounding ground water levels are very high and drainage ditches need to be allowed time to lower before any pumping to these can take place, this is to avoid flooding other locations dependant on the same drainage system.
“Until this situation changes we have no option but to leave the road closed and this is considered the safest option available to everybody affected by the current situation.”
The spokesperson added: “The forecast is that more bad weather is on the way and this, combined with predicted high tides, has the potential to prolong the situation. We are constantly reviewing the situation and as soon as we can take any action we will.
“Until such a time the road will remain shut to ensure the safety of road users and the diversion will remain in place.”