Forecasters are predicting snow will start falling tonight and last into next week.
The Met Office is currently expecting snow to start in Calderdale at around 8pm.
The snow will continue on Saturday, Sunday, Monday and Tuesday.
They could ease off on Wednesday but return again next weekend.
An amber warning for snow has been issued for most of Friday and an ice alert is out for Saturday and Sunday.
Meanwhile temperatures are not expected to reach above -2 degrees celsius today.
Freezing fog this morning will be slow to clear in places and is reported to be causing reduced visibility on the M62.
The weather should stay dry with a few sunny spells during today.