A flood alert has been issued by the Environment Agency for the Upper River Colne and Radlett Brook following heavy rain during the night.
The alert was issued this morning and warns of possible flooding to the Radlett and Borehamwood area with the rain expected to continue into the afternoon.
The Environment Agency says as a result of heavy rainfall river levels could rise quickly and come out of the banks causing flooding to low lying areas and roads.
However the agency also says on its website it does not expect flooding of properties at this stage.
The flood alert is at a level which warns flooding is possible and people should be prepared, with the Environment Agency saying an update is expected later today.
Other areas are already struggling with the heavy rainfall with Allum Lane, in Elstree, partially flooded and cars having to drive slowly through the water.
For more information people can call the Floodline on 0845 988 1188 and select option one.