SONNING Bridge closed at 3pm today (Monday) due to floodwater.
There will be no through-route from the A4 and Sonning Bridge to the A4155.
Meanwhile, riverside homes in and around Henley are at risk of flooding as rain continues to fall.
The Environment Agency this morning issued a warning for properties in low-lying areas between Henley and Medmenham.
The Thames remains high and continues to rise due to rainfall overnight.
Surface water flooding closed the B478 at Playhatch this morning following reports of drivers struggling to get through.
Town and county councillor David Nimmo Smith said: Flooding is already affecting local roads and communities and we all need to be mindful of the hazards of moving around in flood water, be that travelling in vehicles or on foot or bicycle.
Be a good neighbour please check on those around you, especially in flood-risk areas and lend a hand to those who may struggle to look after themselves.
County council emergency planning officer Bethan Morgan said: We would advise motorists to take extra care on the roads and if in any doubt, not to drive through flood water.
Along with our partners such as the district councils and the Environment Agency, we have been preparing for flooding for some time as you would expect. We have also had staff working hard over the festive period dealing with the effects of the weather.
At the moment there are many flood alerts on watercourses in Oxfordshire and no flood warnings, but even minor rainfall could have an effect in some areas and risk property flooding, so now is a good time to make sure you are prepared.
She added: We would advise residents to visit our flooding web pages if they are at all concerned about flooding as we have put together a range of advice and helpful information on preparing for, responding to and recovering from flooding.