M25 Junction 23: the A1(M) at South Mimms
Junction 23 is where the M25 meets the A1(M), at South Mimms in Hertfordshire. A large oval roundabout sits around the point where the two motorways cross, and South Mimms services are right beside it.
Live traffic speed flow: M25 Junctions 22 to 24
Go to our live M25 traffic speed flow map ›
Where the roads go
Take the A1(M) north for Hatfield, Welwyn Garden City, Stevenage and the North, or the A1 south towards Barnet and London. On the M25, the next junction anticlockwise is Junction 22 for St Albans, and clockwise it is Junction 24 for Potters Bar.
South Mimms services
South Mimms services are reached from the roundabout at Junction 23, so they can be used from either direction on the M25 and from the A1(M). See M25 motorway services for more.
For news about the A1(M) itself, see our sister site A1(M) Traffic.
M25 Junction 23 at a glance
| Junction | M25 Junction 23 |
| Meets | the A1(M) (A1(M) Junction 1) |
| Near | South Mimms, Potters Bar and London Colney |
| Next junction clockwise | J24 (A111, Potters Bar) |
| Next junction anticlockwise | J22 (A1081, St Albans) |
| Traffic news for the A1(M) | A1(M) Traffic |
Live traffic news at M25 Junction 23
Live traffic news at M25 Junction 23
This is the news for Junction 23 only, not the whole M25. For the rest of the motorway see all the latest M25 traffic news, the overhead signs and the speed limits in force now.
Updated 02:57 Sat 3 Oct 2026