Heavy snow and ice are causing problems for commuters, schoolchildren and travellers across Bedfordshire, Buckinghamshire and Hertfordshire.
Some roads have been closed and others are only passable with care.
Luton Airport will remain closed until further notice and the shuttle service between Parkway station and the terminal is suspended.
More than 350 schools are shut in Hertfordshire, over 60 in Luton and about 88 in the rest of Bedfordshire.
More snow is expected later and more schools are likely to shut.
Power cuts are also being reported in parts of Hertfordshire.
The Arriva bus company has suspended all services in Stevenage, Hemel Hempstead and High Wycombe but will attempt a normal service in Milton Keynes.
Hertfordshire Police say they have dealt with more than 400 emergency calls through the night.
The A505 between Hitchin and Luton is closed and the A507 between Baldock and Royston is not passable.
Another badly affected area is west of Hemel Hempstead towards Tring on the A41 where there have been a series of jackknifed lorries.
Police say they have struggled to reach them as conditions are so treacherous.
The M40 is closed both ways in Buckinghamshire due to a serious accident involving two lorries, a coach and a car between junctions 4 and 5.