UPDATE: After a test journey on the tracks this morning, First Great Western have said that it will now be mid-afternoon before the main railway into Cornwall is reopened.
Replacement coaches will be running instead this morning.
Passengers are being advised to check with First Great Western before travelling.
Branch lines are open across the county except Looe valley line.
EARLIER:The main train line into Cornwall will reopen today after Friday night's storm suspended all services yesterday.
First Great Western (FGW) said the first service will leave from Plymouth at 10.30am but will only go as far as St Erth as Penzance station remains closed.
Jayne Jones, of FGW, said a limited service will run throughout the day, with coach transfer available for areas which can't be reached on the train line.
All branch lines are now open throughout the county except Looe Valley line which suffered greater flood damage.
Ms Jones said Penzance station is likely to remain closed for some time.
She added: "There is damage to a signal. Network Rail are still investigating."
Refunds are available to customers affected by the service changes.
Passengers are advised to check services at firstgreatwestern.co.uk/traveladvice before travelling today.