Both carriageways of the M25 between junctions 22 and 21A were closed on 18 July 2026 after a large warehouse fire broke out near St Albans, prompting fears of a secondary explosion. Hertfordshire Fire and Rescue was called to the blaze at Ventura Park, Old Parkbury Lane, Colney Street, at 09:21 BST, and 15 fire crews were sent to the scene.
National Highways said the motorway had been shut because of the risk of a further blast, along with smoke and debris that could affect the carriageway. Residents in the area were told to keep their doors and windows closed and to avoid the vicinity while crews worked to contain the fire.
Why was the motorway closed?
The closure was ordered because of the danger posed by the fire itself and the possibility of a secondary explosion at the site. Hertfordshire Police confirmed that the M25 shutdown was directly linked to smoke from the warehouse fire, and additional road closures were put in place locally at Colney Street and Old Parkbury Lane in St Albans.
Who is responding to the incident?
According to LBC, Deputy Chief Fire Officer Mark Barber said crews were tackling a fire at a large industrial unit in Ventura Park, Old Parkbury Lane, Colney Street, St Albans. National Highways noted that because the warehouse sits close to a railway line, Network Rail had a representative on site liaising directly with fire crews to manage the risk to rail infrastructure.
The fire service said it had:
received a significant number of calls regarding this incident
A spokesperson for the service added that firefighters were:
working hard to bring the situation under control
How badly is traffic affected?
Motorists face delays of around 60 minutes in both directions on the approach to the closed stretch of the M25. National Highways urged drivers to allow significant extra time for their journeys and to consider alternative routes while the closure remains in place.
Has a similar incident happened before?
This is not the first time a large fire has caused major disruption on or near the M25 in recent weeks. In June 2026, the M25 anti-clockwise in Essex was closed between junctions 26 and 28 after two separate lorry fires disrupted the morning commute, and in July 2026 firefighters also tackled a large blaze at an Essex industrial unit following reports of an explosion-like sound.
What else is known about fire-related disruption in the area?
A separate incident involving a trackside fire near Waltham Cross previously halted trains between London and Stansted Airport, Cambridge North and Hertford East. A later report on that incident said Hertfordshire Fire Service told residents near Station Approach and Waltham Cross railway station to keep their windows and doors shut, and that traffic on the anti-clockwise M25 was moving slowly between junctions 26 and 25 under a 40mph limit, according to a national broadcaster's report.
What happens next?
Fire crews remain at the scene working to bring the blaze under control and reduce the risk of a secondary explosion before the M25 can reopen. Drivers are advised to monitor official updates and avoid the area around St Albans until the closure is lifted.
- M25 closed both ways between junctions 22 and 21A from 09:21 BST on 18 July 2026
- Fire broke out at a warehouse in Ventura Park, Old Parkbury Lane, Colney Street, St Albans
- 15 fire crews deployed amid fears of a secondary explosion
- Local road closures in place at Colney Street and Old Parkbury Lane
- Roughly 60-minute delays reported in both directions on approach roads
