Almost half a month's worth of rain is expected in parts of Cornwall today along with gusts up to 80mph.
The Met Office which has issued an amber warning - 'be prepared' - for flood and storm force winds.
The storm warning comes as Cornwall Council announced it is handing out free sandbags to everyone affected by floods.
The Environment Agency is warning of possible flooding all along the south coast of Cornwall later this afternoon.
A Met Office spokesman said: "A spell of heavy rain is expected to affect much of Cornwall during Friday morning, clearing to the east during the afternoon - 15-25 mm of rain will fall widely within the amber warning area with 40 mm possible in a few places.
The conditions are due to yet another storm which is developing to the west of the Azores.
The heaviest rain will affect southwest England during Friday morning, clearing to the east in the afternoon.
Met Office spokeswoman Nicola Maxey said average rainfall for the whole of February is 101mm.
Last month was the wettest January on record since 1988.
A further period of very strong winds is possible from Friday afternoon, overnight into Saturday morning.
The spokesman said: "Gusts of 70 mph are likely in the amber warning area with isolated 80 mph gusts possible along most exposed parts of the south coast. Winds will ease from the west during Saturday morning.
"The public should be aware of the potential for disruption to travel as well as trees being uprooted and perhaps damage to buildings.
The very strong winds will be accompanied by large waves along the south coast and the public should also be aware of these potentially dangerous conditions and also the possibility of coastal flooding."
An Environment Agency spokesman said: "Strong winds, tidal surge and large waves are expected to cause flooding at exposed locations over the high tide on Friday evening.
"Locations with damage to defences, buildings and structures, will be especially vulnerable to the predicted large waves. These locations include: Penzance, Newlyn Green, Marazion, Longrock, Porthleven, St Mawes, Pentewan, Looe, Seaton, Kingsand, Cawsand and Plymouth."
High water is between 16:41 at Newlyn and 17:49 at Plymouth.