Extreme Weather In Rail

February 1, 2023
Learn how construction contracts define "exceptionally adverse weather conditions" and what you should do if you're impacted by extreme weather.

How Does Your Contract Define Extreme Weather?

Delivering rail projects is difficult. You’re dealing with large scale projects, different access types, subcontractors and client demands. These conditions are made even worse by extreme and unforeseen weather conditions.  Extreme weather causes work disruption, resource wastage, significant project delays and, eventually, financial losses for both the contractor and the client.

Construction contracts generally include weather-related clauses addressing when, and to what extent, the responsibilities and consequences of adverse weather are to be shared or compensated. 

However, setting clear and objective limits for abnormal weather is problematic, starting with the lack of agreement about which weather conditions can be considered as "normal" or "average". 

What is adverse weather?

Most construction contracts will use the term ‘exceptionally adverse weather conditions’ (or similar), however not all will provide a definitive explanation of what this means.


The NEC Engineering contract refers to weather events that are proven to occur on average less frequently than once in ten years. This is substantiated by reference to an established climate data source for a specified location.


JCT contracts simply refer to ‘exceptionally adverse weather’ however, recent case law often directly links to a comparison of the previous 10 years of meteorological records for the site.


The ICC 2011 defines weather events as ‘exceptionally adverse weather conditions’. As with JCT, the definition is very broad and the Employer Representative will usually assess whether the weather is sufficiently adverse. Historical records are beneficial, however, it is not clear how far back these records should go as requirements are not as clearly defined as NEC.


FIDIC 2017 defines weather events  as “Adverse climatic conditions at the site which are unforeseeable, having regard to climatic data made available by the Employer under SubClause 2.5 … and/or climatic data published in the Country for the geographical location of the site". 

Whether weather is sufficiently adverse is determined by the Engineer.

In the absence of any specific provisions within the contract, a Met Office weather warning for weather conditions that are likely to cause delays (such as snow or wind) in the relevant area may well be sufficient, but this will depend on the attitude of each individual employer.

As a general rule, the key word within the phrase is ‘exceptionally’. Whilst snow in May would likely allow the contractor to claim an extension of time, snow in December would probably not.

What Happens When I Am Impacted By Weather?


  • The Contractor has to notify the Project Manager of a compensation event “within eight weeks of becoming aware that the event has happened”.
  • If notice is not given, the Contractor loses its right to any additional money or time.


  • The Contractor has to notify the Architect/Contract Administrator/Employer (depending on the contract) as soon as it realises that completion of the works is or is likely to be delayed.


  • The Contractor has to notify the Employer's Representative (ER) “within 28 days after the cause of any delay” with detailed particulars.
  • The ER must make an assessment upon receipt of the particulars of the delay and notify the Contractor. If the ER finds that the Contractor is entitled to more time, it grants an interim extension of time.
  • The ER must “no later than 14 days after the due date or extended date for completion of the works” proactively consider whether an extension of time should be given, whether or not the Contractor has asked for time to be extended.
  • The ER is to make a final decision on the overall extension of time granted under the contract “within 28 days of the issue of the Certificate of Substantial Completion”.


  • The Contractor has to notify the Engineer describing the event giving rise to the cost or delay “as soon as practicable, and no later than 28 days after the (Contractor) became aware or should have become aware” of the event.
  • If the Engineer considers that the Contractor has failed to give notice of its claim within the 28 day period, it notifies the Contractor within 14 days of receiving the Contractor's claim (giving reasons). If the Engineer does not give such notice, the Contractor's notice of claim is deemed to be a valid notice.
  • The Contractor keeps such contemporary records as necessary to substantiate its claim.
  • The Contractor has to provide a "fully detailed Claim" as defined by Sub Clause 20.2.4 within 84 days of becoming aware (or when they should have become aware) of the delay event.

How Should My Business Deal With Adverse Weather?

When making or considering claims for adverse weather, parties should ensure they comply with the terms of the contract - including giving and responding to notices in time and providing all information required. Ideally, records of weather changes should be kept and updated regularly to assist with any claims that may need to be made.

1. Understand Risks

Standard contracts are often heavily amended when they flow down from client to contractor to subcontractor. It is therefore important that contract provisions should be thoroughly checked. 

All contract parties should fully understand how the weather risks are apportioned before signing.

2. Keep Detailed Records

Daily diaries are essential — and should clearly describe the severity of the weather and how it affects performance as well as which resources were impacted. 

To succeed in a weather delay claim, the contractor must also establish that its performance was actually impacted by weather. This requires analysis of critical path activities — those driving the completion date. Delay due to noncritical path activities will not suffice.

Construction programmes are crucial. For any claim involving a weather delay, the programme and the daily diaries should work together to tell a story about the severity of the weather event and its effect on the project completion date.

3. Communicate With Your Client

Notifying the client (Employer Representative/Engineer), is key to gaining extension of times and being successful with any claims. Contractors should ensure that their teams fully comply with the notice requirements - both time and information – to ensure that they are not excluded or time barred. 

How Can Raildiary Help?

The Sitediary app automatically captures weather conditions at your location and attaches it to all daily reports. This ensures that essential information is always recorded, giving project management teams the confidence that they are covered should the worst arise.

Raildiary's weather report includes:

  • Temperature
  • Wind speed
  • Precipitation
  • Humidity

In conclusion, extreme weather can be a major challenge for contractors in the construction industry, causing work disruption, resource wastage, significant project delays, and financial losses. Most construction contracts have weather-related clauses that define adverse weather and outline the responsibilities and consequences for both parties. However, there is a lack of agreement on what constitutes "normal" or "average" weather conditions, making it difficult to set clear and objective limits for abnormal weather. Contractors should ensure they comply with the terms of the contract when making or considering claims for adverse weather, including giving and responding to notices in time and providing all required information. Keeping detailed records and communicating effectively with clients is also crucial for managing the impact of adverse weather on construction projects.

Extreme Weather In Rail

Will Doyle


I am an experienced RICS chartered Quantity Surveyor​ with first-hand experience of how the consistent capture and analysis of data can transform global project delivery.

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