Thick fog has caused disruption to a number of flights due to fly in or out of Cardiff Airport.
The 8:00 FlyBe service to London City Airport has been cancelled, while services to Edinburgh, Anglesey and Paris have also been delayed.
A flight due to arrive at the airport from Dublin at 9:30 has also been cancelled.
There are delays of up to 45 minutes and some cancellations on Arriva Trains Wales between Wrexham General and Chester because of a fault with the signalling system,.
There are hazardous driving conditions and there is slow traffic because of fog and a rolling road block on the M4 Second Severn Crossing.
Visibility is reduced in both directions between J23 M48 and J22 M49. There's a 30 mph speed limit.
A road crash is causing delays on the A470 north of Cardiff this evening.
There is stationary traffic after up to four vehicles were involved in the incident between Cardiff Road / Gwaelod-Y-Garth Road (Upper Boat Interchange) and A4054 Pentrebach Road / A473 (Glyntaff Interchange).
Officers are enroute to an RTC on the A470 Northbound between Rhydyfelin and Pontypridd. Delays are expected. One lane is blocked
Traffic Wales says one lane is also blocked and there is queueing traffic due to accident of up to five vehicles involved on M4 Westbound between J33 A4232 (Cardiff West And Services) and J34 A4119 (Miskin).
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South Wales Police says the A470 south is closed at Rhyd y Car to Pentrebach due to a lorry fire.
The M4 is closed in both directions in Margam following two serious accidents earlier this morning.
The westbound carriageway is closed between J38 and J39, while the eastbound carriageway is closed between J38 and J42. Traffic is queueing and diversions are in place in both directions.
We are in attendance at a road traffic collision on the M4 junction 38-39 near Margam. The road is closed both ways. ^cy
Traffic has returned to normal after an earlier accident on the A4810 (Eastern Distributor Road) in both directions between the M4 J23A (Magor Services) and Llanwern Steel Works (Tata Steel).
There is slow traffic after an accident, now on the hard shoulder on the M4 Briton Ferry Bridge Eastbound between J42 (Earlswood Roundabout/Fabian Way) and J41 (Baglan/Pentyla).
All lanes have been re-opened.
One lane is closed and there is queueing traffic after an accident on the M4 Briton Ferry Bridge Eastbound between J42 (Earlswood Roundabout/Fabian Way) and J41 (Baglan/Pentyla).
The A4810 Queens Way (Eastern Distributor Road) is closed in both directions and there is queueing traffic after an accident.
It involved a motorcycle between the M4 J23A (Magor Services) and Llanwern Steel Works (Tata Steel).
The collision is near to Gwent Europark and Tesco Distribution Centre.
It's affecting traffic from J23A of the M4 towards the South of Newport, with queues and congestion for the M4 slip roads at J23A.