It was reported this week that some work on the Aquatics Centre at the 2012 Olympic park had to stop due to the weather and, given conditions currently prevailing over much of the UK, this will not be the only site affected. This raises questions of what contractual remedies might be available for the delays and costs caused by the current cold snap. The remedies available vary from contract to contract with some containing more generous provision than others so it is worth checking the provisions applicable to each project individually.
The JCT and SBCC standard forms include as a Relevant Event, entitling Contractors to extension of time, "exceptionally adverse weather conditions". This is not a Relevant Matter, however, and so there is no corresponding entitlement to loss and expense as a result. That of course raises the question of what are "exceptionally adverse weather conditions". This term is not defined in the contract but can probably be established by comparing current conditions to previous years' weather records.
Bad weather on its own is not enough and it is of course also necessary to establish that there is a causal link between the weather and the delay - in other words to show that progress of the works has been delayed as a result of the weather. As always, record keeping will be key for this.
NEC 3 has a more elaborate provision based on an objective test. It includes as a Compensation Event that a weather measurement is recorded within a calendar month, before the Completion Date and at the place stated in the Contract Data, the value of which, by comparison with the weather data (specified in the contract) is shown to occur on average less frequently than once in 10 years. Only the difference between the actual weather and the average expected weather is taken into account to assess a compensation event which means the contractor remains on risk for weather which the weather data shows is likely to occur within a 10 year period.
On a procedural point, if you are considering a claim for delay as a result of the weather, check the contract to make sure you comply with the notice provisions. Some contracts, particularly the NEC, go into some detail on requirements for notices.
The GC/Works/1 Edition 3 specifically excludes weather conditions from the list of matters entitling a contractor to an extension of time and GC/Works/7 does not mention weather at all, so that in these cases weather would be at the contractor's risk.
Some contracts may contain a general provision allowing time for circumstances outside the contractor's control and it will be a matter of considering each project on its own merits to decide whether this is likely to give any remedy for weather delays.