Torrential downpours are expected to blight parts of the county still suffering the after effects of recent heavy rain.
The Met Office has issued a yellow weather warning for rain in south west Hertfordshire as forecasters predict further deluges and gale force winds.
The rain is expected to arrive on Wednesday and Thursday and could lead to flooding and travel disruption as the already sodden ground struggles to cope with the extra water.
Radlett Brook burst its banks on Friday, flooding the station car park and threatening to deluge some homes.
The Met Office’s chief forecaster said: "Another Atlantic depression is expected to bring a spell of heavy rainfall and strong winds to parts of the UK later on Wednesday, perhaps lasting into Thursday.
"The track and intensity of the depression is currently very uncertain, meaning that confidence in rainfall amounts and distribution across the UK is low.
"Falling soon after earlier widespread rainfall, the cumulative effects of these weather systems are likely to exacerbate the current flooding situation."
The warning is in place from 3pm on Wednesday until 12pm on Thursday.