Many of the standard forms of construction contract make some provision for adverse weather within their clauses and some forms are more specific than others. For example, the NEC form specifies that the weather must be shown to have occurred less frequently than once in ten years when compared to the weather data place. This is normally the closest meteorological station to the location of the works and should be specified in the contract data.
The JCT standard form refers to exceptionally adverse weather conditions. The problem is that exceptionally adverse weather is not defined by the JCT contract. There is also little judicial interpretation or authority on the matter.
One of the legal cases from which guidance may be sought is Walter Lawrence & Sons v Commercial Union Properties Ltd [1984] 4 ConLR 37. Severe weather occurred during the works and the contractor applied for an extension of time. The architect assessed the impact of the adverse weather against the planned programme of works and awarded an extension of less time than was applied for. A dispute arose, and the judge decided that the correct test was whether the weather was exceptionally inclement at the time the works were actually carried out, not when the works were planned to be carried out.
As well as proving that the weather was exceptional a delay due to the weather also must be proved. It follows that works susceptible to the weather are more likely to be impacted by exceptional weather rather than those works which are sheltered from the weather. This may seem obvious but often the impact of adverse weather is applied right across the programme irrespective of the type of activity in progress.
Both the assessment of the exceptionally inclement weather and the delay caused are at the discretion of the awarding party. Perhaps a more robust approach is to analyse the impact retrospectively, ascertaining if a critical delay did occur and what the cause of that critical delay was. That may or may not be a weather event but if it is then it needs to be shown that it was exceptional. The risk of weather that is not exceptionally inclement rests with the contractor and a suitable allowance must be made in the programme.
