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.
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Rain this evening with showers expected tomorrow and minimum temperatures overnight of 9 deg C 9 66 deg F)
Early fog will clear to leave a dry day with sunny spells and highs of 18 deg C (64 deg F)
Overnight there'll be mist and fog but it will clear for Sunday leaving sunny spells.