Police are advising drivers to avoid the M25 until mid-afternoon after a lorry fire closed the carriageway on both directions in Hertfordshire.
The section between junctions 21a and 23 near the South Mimms services is expected to be closed until 3pm.
Long tailbacks have built up on surrounding roads.
More top news
The Duke and Duchess of Cambridge have been seen for the first time in public with both their children at Sandringham.
Any remaining heavy showers should clear to leave a dry night. Lows of 12 deg C.
Princess Charlotte will have five godparents - two less than her brother Prince George. This is who the royal couple have chosen.