Areas including Sonning, Maidenhead, Windsor, Datchet, Egham, and Staines could be affected.
With dozens of smaller rivers and tributaries feeding water into the River Thames, levels downstream of Abingdon will continue to rise over the next two to three days and residents living along the Thames are being urged to take action to reduce the impact of any flooding.
There are currently 50 flood warnings and 78 flood alerts in place for the South East.
A flood warning means that flooding of property is expected and that people should take action to prepare.
Environment Agency teams continue to be out in force monitoring water levels, checking and operating defences, working with partner organisations, issuing warnings and helping communities to prepare.
The Jubilee River flood scheme is in operation, helping divert water away from communities in Maidenhead, Windsor and Eton. Temporary flood defences are in place and protecting properties in the Oxford area.
People are also urged to avoid driving or walking through flood water. Fast-flowing water that is just 15cm deep can be enough to knock an adult off their feet.
Howard Davidson, Environment Agency Director, South East, said: “River levels will continue to rise for the next few days and we expect to see further property flooding over the coming days. We’re paying close attention to the River Thames, particularly below Abingdon, through Berkshire and into Surrey.
“We are expecting that many more properties will flood over the next two to three days, but there is still time for people to take appropriate action. We have had warnings and alerts in place for several days, which stress that flooding is imminent, and now is the time for people to act.
“Environment Agency teams continue to work to work around the clock maintaining flood defences, clearing watercourses and deploying pumps and temporary defences to protect communities at risk, but we want to stress to residents that they need to act.”
Advice for those dealing with flooding is available on the Environment Agency website, on social media @EnvAgencySE #floodaware and by calling floodline on 0845 988 1188.