People in north Lancashire have been urged to monitor river levels close to their homes after the Environment Agency (EA) issued a flood warning.
Water levels have risen in the Burrow Beck in Lancaster following heavy rainfall. Flooding of roads and farmland is also possible.
The EA said river levels in the Colne, Ribble and Calder all set new high level records in recent days.
Rail services between Preston and Carlisle were also suspended.
The line was reopened for northbound trains at 09.:20 GMT, while southbound services began running at 10:10.
Services run by Avanti West Coast from London Euston to Glasgow and Edinburgh via Birmingham were affected, as well as trains operated by Northern and TransPennine Express.
A Network Rail spokesman said: "Because fast moving floodwater can undermine the railway's foundation stones, trains were brought to a stop while our engineers made sure the railway was safe for passengers.
"The West Coast Main Line is open again but with some services delayed people are advised to check National Rail Enquiries or with their train operator for the latest travel information."
Avanti services were already affected by speed restrictions in Cumbria and north Lancashire due to the wet weather increasing the risk of landslips and flooding.
Trains on a section of the West Coast Main Line between Lancaster and Penrith were restricted to running at 50mph instead of the normal 125mph between 17:00 GMT on Wednesday and 10:00 on Thursday.
One lane of the M6 southbound between Junctions 33 for Garstang and 34 for Lancaster was closed earlier, due to flooding.
There is a yellow warning for rain across Lancashire and Cumbria until 15:00.
At the beginning of February, flooding from Storm Ciara saw homes flooded in the Ribble Valley, with some residents rescued by boat from their homes.