A flood alert is in place for Lands End, Helston, Crowlas, St Ives, Hayle, Camborne and Perranporth.
The Environment Agency says that while a band of heavy rain that crossed the area overnight is now clearing, to be replaced by isolated heavy showers throughout Friday, river levels are high and ground saturated, with flooding possible.
Standing water has been reported on the roads around Hayle and St Ives while there are reports of drivers abandoning cars on the A394 near Praa Sands.
Treneere Lane in Heamoor and Station Approach in St Erth are both said to be hit by flooding.
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