High groundwater levels mean there is a continued risk of flooding in areas such as south Wiltshire, Hampshire and West Berkshire, says the Environment Agency.
People are 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, says the agency.
Dave Bedlington, for the Environment Agency, said: “We are expecting further heavy rainfall today and into the weekend, which will continue to raise the threat of flooding to communities along rivers and along the south east coast."
Advice for those dealing with flooding is available on the Environment Agency website and from Floodline on 0845 988 1188.
Up-to-date information is available on Twitter by following #floodaware