A Flood Warning has been issued for a river on the border of Gloucestershire and Wales by the Environment Agency.
The warning, which means flooding is expected and immediate action required, is in place for the Wye Estuary in Brockweir on the western boundary of the Forest of Dean and Wales.
Lower-level Flood Alerts are also in place for the Severn Estuary from Gloucester to Sharpness and for the Wye Estuary in Gloucestershire.
"As a result of high tides from Monday through to Wednesday, there is the potential for flooding of some low lying areas.
"This message contains gauge information for Newport Gauge for the tidal peaks on Monday evening and Tuesday morning.
"At Newport; a tide level of between 7.2 and 7.51 metres is expected to occur at 8:45pm [on Monday]. A similar level is expected to occur [Tuesday morning] at 9 am.
"The period of high tides is expected to last until Wednesday, September 12."
This message contains gauge information for Sharpness for the tidal peaks on Monday evening and Tuesday morning.
At Sharpness; a tide level of between 9.8 and 10.4 metres is expected to occur at 9:15pm [on Monday evening].
"As a result of high tides from Monday through to Wednesday, there is the potential for flooding of some low lying areas. This message contains gauge information for Newport and Avonmouth Gauge for the tidal peaks on Monday evening and Tuesday morning.
"At Newport; a tide level of between 7.2 and 7.4 metres is expected to occur at 8:45pm [on Monday evening].
"On Tuesday morning a tide level of between 7.2 and 7.5 metres is expected to occur at 9:00 am.
"At Avonmouth; a tide level of between 14.1 and 14.3 metres is expected to occur at 8:45pm [on Monday evening].