When the skies darken and the weather turns, even the best-planned construction projects can stall. As winter approaches and the prospect of cold, rainy, windswept days looms, developers and construction professionals might wonder how adverse weather might disrupt their site operations — and what steps they can take under their construction contract to protect themselves if progress inevitably stalls.

Exceptionally Adverse Weather Conditions Under JCT contracts

Some JCT contracts, including JCT Standard Building Contracts, Design and Build Contract and Intermediate Building Contracts, provide for the Contractor to be entitled to an extension of time in respect of delay caused by “exceptionally adverse weather conditions”, although this is not defined. There is also no mechanism for determining whether such conditions have arisen.

For more details on the procedure to follow to claim/grant an extension of time, please read our A-Z blog on Extensions of Time: Understanding Extensions of Time in Construction Contracts (section “Procedures to apply for an extension of time – overview”)

What constitutes “exceptionally adverse weather conditions”?

In some circumstances, it may be obvious to the parties that the weather conditions are “exceptionally adverse”, such as in the case of severe flooding caused by torrential rain. However, in other cases, it may not be so easy, and disputes might arise between the parties as to whether heavy rain, snowfall or strong wind constitutes “exceptionally adverse weather conditions” under their contract.

As a starting point, weather might be considered as exceptionally adverse in several respects—for example, due to its degree or intensity (such as temperature or wind speed) or its duration (such as in the case of rainfall, winds or blizzards). This approach would require consideration of conditions of the typical or ‘average’ weather for the site’s location at that time of year.

When deciding, parties may therefore consider:

• data and reports – such as obtaining Meteorological Office data and reports in respect of the relevant area, at the relevant time of year, or reports from reliable news sources describing the weather as exceptional, and the damage caused;
• parties’ records and other information – parties should maintain their own records of site weather conditions and their impact on the works. These records could include on-site measurements, site diary entries, photographs, or video footage showing the weather and any resulting damage or disruption.

It is worth noting that other standard contracts such as NEC have taken a different approach to weather conditions than the JCT, and contain a much more prescriptive test for determining when weather entitles the Contractor to an extension of time.

For example, in NEC4 ECC, if the contractor intends to claim an extension of time for bad weather, it needs to obtain weather measurements for each calendar month from the source stated in the Contract Data Part One, and compare the actual measurements for that month with the historical weather data for each of the categories. If any of the actual measurements is shown to occur less than once every ten years, the contractor will be entitled to a compensation event for the difference between the actual and historic measurements.

Parties may wish to include similar provisions in a schedule of amendments to the JCT clarifying when weather conditions will constitute a “Relevant Event” entitling the Contractor to an extension of time, for more certainty and to avoid disputes down the line. This is likely to depend and vary on each project – for example, internal refurbishments are unlikely to be affected by heavy rainfalls, whilst projects relying heavily on using cranes, such as projects utilising Modern Methods of Construction, might be heavily disrupted by strong winds.

Other considerations in relation to weather events

If the contractor is unable to claim an extension of time for exceptionally adverse weather, it may still consider whether a delay claim could be made on other grounds — for example, if the weather caused damage classified as a Specified Peril (such as lightning, storm, or flood), or, in limited circumstances, whether the occurrence could be treated as an event of force majeure.

Finally, it is worth noting that under JCT contracts, “exceptionally adverse weather conditions” does not constitute a Relevant Matter entitling the Contractor to loss and expense, and each party will have to bear their own costs incurred as a result of disruption to the works due to severe weather.

Key Takeaways for Developers and Contractors

• Obtain Met Office data for the relevant location and time period.
• Compare actual conditions against historical averages.
• Maintain detailed site records, including photographs and diary entries.
• Consider contractual amendments for clarity on weather-related delays.

For advice on exceptionally adverse weather conditions and construction contracts in general, please contact our Construction & Engineering team who will be happy to help – whatever the weather!