The RNLI in Harwich, Essex, started the morning by clearing snow from their lifeboats.

The lifeboat charity said its volunteers are available 24/7 "whatever the weather".

The RNLI crew in Southend carried out an exercise last night as temperatures dropped below -4C.

If you see a homeless person sleeping rough in the freezing temperatures, you can call StreetLink, a charity which helps outreach teams find homeless people on the streets., external

StreetLink will ask for the location of the person sleeping rough and tell the overnight outreach teams, who can take them to a shelter.

More on the schoolchildren in Lincolnshire, whose bus collided with a car and skidded off the road, near Deeping St James.

Lincolnshire Police say none of the 45 or so children have been injured, but are "obviously shocked".

A spokesman said it was one of about 20 collisions in the county this morning caused by the weather.

Four cars were involved in another crash at Old Leake, near Boston, with two others leaving the road due to "very icy conditions".

Leeds Castle, in Kent, might look stunning in the heavy snow - but its doors are closed to the public today. Similarly Lewes Castle, in East Sussex, has also been forced to shut up shop.

It's not just schools shutting their doors today. Chester Zoo and the Welsh Mountain Zoo in north Wales are both closed today.

Meanwhile the National Trust in Wales said it has closed six properties due to snow and ice.

Several train companies have been hit by delays and cancellations, with remaining services expected to be extremely busy.

• National Rail Enquiries says severe weather is affecting services on C2C, Greater Anglia, London Overground, South Western Railway, Southeastern, Stansted Express, and TfL Rail
• Disruption may continue through Tuesday and into Wednesday and Thursday, Network Rail says
• London Overground is running a stripped-back service, with between two and four trains per hour on many routes, and no services on other lines, such as between Romford and Upminster
• C2C is operating a limited timetable and advises customers not to travel where possible
• Greater Anglia is also running a limited service, with less frequent and slower services between Norwich and Ipswich and cities including London and Cambridge
• Trains between Norwich and Lowestoft, Felixstowe and Great Yarmouth are cancelled, among others
• Southeastern says it expects to run a normal timetable on Tuesday, but if conditions worsen an emergency timetable may be introduced

The latest problems reported on the roads are:

• Slow-moving traffic is causing delays on the M2 Kent westbound, between junctions seven and five
• HGVs struggling in the snow have caused delays on the M20 in both directions between junctions eight and nine, adding up to two hours to journey times
• The A249 in Kent remains closed following a crash between two lorries

Meanwhile, dozens of stranded motorists had to be pulled from snow drifts on Tuesday morning, the AA said.

Vince Crane, of the AA, said: "With the sub-zero temperatures this week, drivers should allow extra time to properly de-ice the car and check their route before setting off - try to favour gritted roads if possible.

"Accidents happen when people rush so when on the road, leave plenty of space behind the car in front and drive to the conditions."

BBC Wales News

It may be cold today but how does it compare to the blizzard of January 1982 which gripped large parts of Wales.

The snow fell for 36 hours with drifts reaching up to 6m high (19ft) and temperatures were believed to have plummeted to -20C.

Here is a video from the time.

Dogs, cows, horses and big cats come face to face with the snow - and (mostly) love it.

Image source, Getty Images

Image source, @NenniCook/Twitter

Lincolnshire Police say ice on the roads is causing lorries to slip and get stranded.

Supt Kieran English said the south of the county, especially around Spalding and Bourne, is the worst affected. One of the major problems is at Willingham Hill near Market Rasen.

He says officers are expecting another peak at 15:00 GMT and is advising drivers to take care.

The A15 at Baston will be closed for some time due to a "very serious car crash", Supt English says.

Some readers with longer memories have contacted the BBC to put the cold weather today into context.

Apart from Liverpool, other airports around England say they have been largely unaffected by the weather so far.

Newcastle is fully operational, as are Leeds Bradford, Gatwick and Heathrow.

A spokeswoman for Manchester says some flights have been delayed due to aeroplanes being de-iced and flights to Naples have been cancelled due to bad weather in the Italian city.

Liverpool Airport has closed its only runway but is still advising passengers to arrive for their flights.

A spokesman said the airport hopes to be fully operational again soon.

British Airways has cancelled a number of short-haul and domestic flights to and from Heathrow because of the weather.

The airline said it had agreed with the airport to "proactively reduce" its schedule and is urging passengers to check their flight status, external.

A spokeswoman said the company was "sorry" and was working with passengers to arrange alternative flights.

A spokesman for Heathrow said all runways were open and operational, and "significant disruption" was not expected today or tomorrow.

More details on school closures.

In Conwy, 58 schools have closed, 35 have shut in Denbighshire, 40 in Flintshire, 67 in Gwynedd and 21 on the Isle of Anglesey.

Police in Lincolnshire say there have been 20 collisions already this morning.

In one incident, 45 schoolchildren were rescued from a bus after it came off the road near the village of Deeping St James at 08:15 GMT.

Officers are urging people to take care in icy conditions.

Although there is no legal obligation to provide shelter for homeless people, councils trigger an emergency protocol in severe weather., external

This means when the cold becomes severe enough - usually when the temperature drops below 0C - local authorities open emergency shelters.

In Manchester, fire stations are being used to house homeless people overnight.

Meanwhile in London, the Mayor's office has opened two emergency shelters , externalif the council shelters become full up.

The charity Crisis says rough sleeping can be "deadly" in this cold weather.

About 4,700 people are estimated to be homeless, official figures released last month show.

The BBC has been looking at why it is so cold all of a sudden.

BBC News Scotland

The Highlands have seen temperatures as low as -8.5C recorded in Altnaharra.

In mainland Scotland, a yellow warning for snow is in place from early Tuesday until Wednesday night.

Image source, Braemar Community

An amber warning for Wednesday, meaning there is a possible risk to life and property, covers Central, Tayside, Fife, Grampian, Highlands, south west Scotland, Lothian and Borders and Strathclyde.