The Met Office is predicting more than 1.9in (50mm) of rain will fall in Wales and south west England and has issued severe weather warnings for both regions.
By tomorrow, the warnings extend to the West Midlands, London and south east England and on Saturday to Yorkshire, the Humber and the north east.
It means the UK is set for more downpours and dashes hopes of an 'Indian summer' - a late season summer spell - after one of the darkest, wettest Augusts on record.
Met Office forecaster John Hammond said: 'The chart is looking very autumnal. It's an early taste of autumn following on from a pretty unsettled August.'
Some areas of the country are expected to suffer localised flooding when the heavy rain and gusting winds move in.
The dank conditions will roll in from the Atlantic today, with rain expected for most of the UK.
Conditions will then worsen tomorrow before petering out over the remainder of the weekend.
