I wonder if the term 'unemployment' could be misleading here - the staff are still employed during the bad weather, they just aren't working (if you know what I mean!).

The terms 'shortage' and 'stoppage' of work are used in some official docs of European countries, particularly Germany and Austria, dealing insurance for building sector workers.

http://www.eurofound.europa.eu/eiro/1999/06/inbrief/de990621...

'The bad-weather allowance was originally introduced in 1959 as a special form of short-time working allowance for construction workers during the winter period. Between 1 November and 31 March each year, the state provided a bad-weather allowance through the Federal Employment Service (Bundesanstalt für Arbeit) in the event of an temporary work stoppage due to bad weather. The aim was that the payment of the bad-weather allowance should prevent construction employers from making their workers redundant in such circumstances.'

http://www.ssa.gov/policy/docs/progdesc/ssptw/2004-2005/euro...

Bad weather allowance: Paid to construction workers whose work is halted because of bad weather. The allowance is payable after the 100th hour of stoppage between November 1 and March 31 of any year.