Flooding on the M40 near Gaydon has forced the closure of Warwick Services and long tailbacks on the motorway.
The service areas in both directions have been flooded and closed indefinitely after heavy rain.
Eyewitnesses said flooding was as deep as a foot in some places. Traffic has been slow or queuing for miles, with visibility badly hit by rain and spray.
The bottleneck began in the early-evening rush hour and motorists have been advised to avoid the area.
At one stage, queues began at junction 15 at Longbridge and stretched into Cherwell Valley, in Oxfordshire, at junction 10.