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
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NOTE: The speed flow, overhead sign messages or other information shown on our live traffic speed flow map is updated every few minutes. We cross check the data and aim to provide warnings if there could be a delay or an inaccurate speed reading. There can be occasions, beyond our control, and despite our best efforts where the speed flow could be inaccurate. We cannot therefore guarantee the speed you can expect on any stretch of the motorway is always accurately shown. However we hope you will find our live traffic speed flow map a useful tool in trying to plan your journey. Safe driving.
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
Incidents and roadworks between Junction 22 and Junction 24 that we are aware of.
M25 Clockwise Jct 23 to Jct 24 Hard Shoulder Closure
01:23 (1:23am)14 Oct 2026reported 48 min ago
- Location
- M25 clockwise between J23 and J24
- Direction
- Clockwise
- Lanes closed
- Hard shoulder closed
- Reason
- Tree and vegetation cutting work
- Schedule
- 09:30 (9:30am) Wed 14 Oct 2026 → 16:00 (4pm) Wed 14 Oct 2026
Forecast - not confirmed
+ 1 more near Junction 23 - see all the M25 traffic news →
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 02:12 (2:12am) Wed 14 Oct 2026