Snow has fallen across most of Wales, causing events to be cancelled and some travel disruption.
Up to 10cm (4in) of snow was expected in many areas, but high ground could see 15-25cm (6-10in).
An amber "be prepared" warning which the Met Office issued for south-east and mid Wales has been downgraded to a yellow "be aware" for snow and ice.
Flights at Cardiff Airport are returning to normal after earlier delays.
French fans had faced a wait as they returned home after the Six Nations match in Cardiff because a number of flights were cancelled on Sunday morning.
Cardiff City's Championship match at Derby also fell victim to the weather - a move branded "disgraceful" by Bluebirds manager Neil Warnock.
Inspections are being carried out at schools across Wales before decisions are made on whether to open on Monday.
It has already been confirmed at least 150 schools in Blaenau Gwent, Caerphilly, Merthyr Tydfil, Monmouthshire, Neath Port Talbot, Powys, Rhondda Cynon Taff and Torfaen will be closed.
I've never seen this many people at Cardiff Airport before...glad I'm not in that queue! pic.twitter.com/vLw0odVTct— Jess (@TiobraidArann1) March 18, 2018
The amber warning - the second most severe Met Office weather warning - was due to be in effect until 21:00, but it was downgraded at about 13:00.
The yellow one for snow and ice lasts all of Sunday and covers most of Wales.
People on social media reported snow falling in all corners of the country, although in some parts, such as Swansea and Llanelli, it seemed to be lighter.
Following an earlier power cut in Caerphilly, which affected about 100 properties, some 24 homes were still without power on Sunday evening.
A number of rural roads were blocked by snow, including the A476 in Carmel, Carmarthenshire, while there were hazardous driving conditions on the Bwlch, Rhigos and Maerdy mountain roads in Rhondda Cynon Taff.
The A470 was closed in both directions between the A487 at Gellilydan and the B4391 at Blaenau Ffestiniog in Gwynedd.
South Wales Police tweeted to urge motorists to drive to the conditions and said a 4x4 had skidded off the A48 in Bridgend.
North Wales Police tweeted: "Snow is affecting routes throughout North Wales - please only make essential journeys."
Cardiff Airport cancelled or delayed most flights in the morning, but by midday the airport said the runway had been cleared and flights were ready to take off.
This is downstairs in Cardiff Airport where the queue starts for security! Airport bustling with French supporters who can’t fly home because of #uksnow @BBCBreaking @BBCWalesNews @WalesOnline @heartwalesnews Never seen Cardiff Airport so busy! pic.twitter.com/xIVrJVR5wP— Jon (@jontutoring) March 18, 2018
Arriva Trains Wales said heavy snow had blocked lines between Newport and Hereford and all services through these stations had been disrupted.
Services between Llanhilleth and Ebbw Vale Town were also affected, along with Wales and the borders trains.
Cardiff Bus said it had planned to continue to run the majority of its services.
First Cymru Buses tweeted: "Many areas have experienced snow overnight which may affect services today."
A number of lorries were also understood to be stuck on the A40 Ross-on-Wye road near Monmouth.
Traffic Wales said long delays were likely on the Severn Bridge after one lane was closed in both directions because of high winds.
Many councils had gritted main roads overnight and said they would continue to try to clear roads throughout Sunday, but warned people to take care on side roads.
Crews have been working throughout the night and will continue to do so today to tackle the weather. Mountain roads are currently closed as work is focused on our main network. pic.twitter.com/1oUePkZDR2— RCT Council (@RCTCouncil) March 18, 2018
The Cardiff City away game against Derby, which was due to start at midday was postponed, while the FA Wales Youth Cup semi final between Connah's Quay Nomads and Swansea Academy was also off.
The Newport Half Marathon, which was rescheduled to take place on Sunday after it was postponed because of snow two weeks ago, was once again called off.
In a statement posted on Facebook on Saturday organisers said: "It's with a very heavy heart we have to once again cancel the Admiral City of Newport Half Marathon.
"The safety of everyone concerned is paramount and with the current forecast of snow, ice and a wind chill of -10 we simply cannot go ahead."
Racing was abandoned at Ffos Las racecourse in Trimsaran, Carmarthenshire and the University of South Wales said all non-essential services such as the sport centre had been closed,
However, the Motorpoint Arena in Cardiff confirmed that Sunday evening's Paloma Faith concert would go ahead as planned.
The Welsh Ambulance Service advised patients to think twice before calling 999 because of the snowy weather and asked people who felt unwell to contact NHS Direct first.
Across Wales the service said it had not had any weather-related problems so far.
People are being urged to check council websites on Sunday for the latest information on whether schools will close on Monday.
Cardiff Council said most schools should be able to open as normal, although the final decision would be made by individual head teachers.
School transport in the city is also expected to be fully operational, although there could potentially be some slight changes to normal arrangements for special schools.
The University of South Wales said staff would be working all day to clear all campuses with the aim to open as normal on Monday. It said staff and students should check updates on its website and social media.
School closure information