UPDATE: Fifth crash on M6 within four hours
The latest accident, just before 10am, required fire crews to cut a man out of his vehicle on the southbound carriageway at junction 29, Clayton Brook.
Two lanes have been affected by the multi-vehicle collision, and delays are back to Junction 30.
Earlier in the day, at 6am a car and lorry collided on the southbound carriageway near junction 33 at Galgate.
Just before 8am on the northbound carriageway between junctions 33 at Galgate and 34 at Lancaster, another crash saw vehicles blocking live lanes.
At 8.30am, a car lost control and hit the central barrier on the southbound carriageway at junction 29 near Clayton Brook.
No details on injuries have yet been released.The North West Motorway Police said heavy rain was affecting driving conditions, with some reports of standing water on carriageways.
Motorists are being urged to reduce their speeds.