The notice that is not issued is the entitlement that is lost
In construction, weather is one of the most commonly cited causes of delay. It is also one of the most avoidable causes of lost entitlement — not because the weather did not happen, but because the required notice was never issued.
Most standard form construction contracts require the contractor to issue some form of early warning or notice of delay when a weather risk appears. The purpose of this requirement is straightforward: it gives the Employer and Superintendent timely information, allows the parties to consider mitigation options while the risk is still prospective, and creates a contemporaneous record of the event before it becomes a claim dispute.
When the notice is not issued — or is issued late, or is too vague to constitute a proper contractual notice — the entitlement is at risk. In many contract forms, this is not a discretionary matter. The contract is explicit: late notice can extinguish the right to claim, regardless of how disruptive the weather was.
The notice is not a formality that can be deferred until the claim is written. It is the contractual act that preserves the right to make the claim at all.
When to issue an early warning notice
The timing obligation varies by contract form, but the underlying principle is the same across all major standard forms: the notice should be issued as soon as the contractor becomes aware — or should reasonably have become aware — of a risk that may affect the completion date, cost or quality of the works.
For weather, this typically means issuing the notice when:
- A forecast shows conditions that are likely to exceed the trade-specific thresholds for planned operations in the next few days
- Actual weather conditions on site have already exceeded the contractual threshold for adverse or exceptional weather
- A sustained period of adverse weather is developing that is likely to affect multiple planned operations over multiple days
- Forecast or actual conditions are approaching a threshold where the contractor may need direction from the Employer before deciding how to proceed
The critical word is prospective. An early warning notice for weather is most valuable — and most clearly satisfies the contractual obligation — when it is issued before the impact occurs or while it is still occurring. Issuing it after the fact weakens both the notice and the eventual claim.
Notice requirements under the major standard forms
Each major contract form approaches the notice obligation differently. Understanding the specific requirement for the governing contract is essential — the notice must meet the wording of that contract, not a generic idea of what an early warning should contain.
NZS 3910 (New Zealand)
Under NZS 3910, the contractor is required to give written notice to the Engineer as soon as practicable after becoming aware of any circumstance that has caused or may cause delay to the completion of the contract works by the due date. The notice should identify the circumstance and its anticipated effect on the programme.
NZS 3910 gives the Engineer a broad role in managing delay events, including weather. The notice is the mechanism by which the Engineer is made aware of the risk. Absent a proper notice, the Engineer — and through them, the Principal — cannot exercise the oversight role the contract contemplates. This is a core reason why courts and arbitrators give weight to the notice requirement in NZS 3910 disputes.
The clause also provides that the contractor must take all practicable steps to minimise the delay. The notice is a natural vehicle for identifying what mitigation steps are being considered and whether the Employer's direction is needed.
AS 4000 (Australia)
Under AS 4000 (and its common variants AS 2124 and AS 4902), the contractor must give notice of a claim for extension of time within the time specified in the contract, and in any event must give notice as soon as reasonably practicable after the cause of delay becomes apparent. The time limits in the contract are strictly applied — Australian courts have been willing to deny EOT claims where the notice was late, even by a small margin.
The notice should identify the cause of the delay, the activities affected, and the extension of time being sought. For weather, this means identifying the forecast or actual conditions, the trade operations affected and the anticipated programme impact.
Many AS 4000 contracts also carry a "time bar" clause that explicitly renders late notice fatal to the claim. Where this applies, there is no discretion: the entitlement is gone if the notice is late.
NEC4 (UK and international)
NEC4 operates an early warning mechanism as a core project management tool, not just as a notice regime for delay claims. Under clause 15, both the Project Manager and the Contractor are required to give early warning of any matter that could increase the total of the prices, delay completion, or impair the performance of the works in use. The Contractor's obligation is active — both parties are expected to identify and communicate risks early.
For weather, this means notifying the Project Manager when forecast or actual conditions could affect the programme, cost or quality of the works. NEC4 also uses a risk register process: early warnings are recorded in the risk register, and a risk reduction meeting may be convened to consider mitigation options.
Weather becomes a compensation event under NEC4 clause 60.1(13) when it occurs less frequently than once in ten years at the project location for the weather measurement stated in the contract. This is a statistical threshold — the actual conditions must be benchmarked against historical data to establish whether they qualify. The early warning notice should be issued when the risk of qualifying conditions appears, not only after the threshold has been exceeded.
JCT (UK)
Under JCT contracts (DB 2024, SBC/Q 2024 and related forms), the Contractor must give written notice to the Contract Administrator as soon as it becomes or should reasonably have become apparent that the regular progress of the works is likely to be materially affected by a Relevant Event. Exceptionally adverse weather conditions are a listed Relevant Event in JCT contracts.
The notice must identify the Relevant Event and explain the likely delay effect. The Contract Administrator then reviews the notice and grants an extension of time if satisfied that the delay is caused by the Relevant Event and affects the critical path.
JCT does not impose a strict time bar in the same way AS 4000 does, but a failure to give timely notice can deprive the Contract Administrator of the information needed to act, and may affect how a tribunal views the strength of the claim. The obligation to give notice early — when the risk appears, not when the impact is certain — is important for the same reason it is important under all other forms: contemporaneous records carry more weight than retrospective ones.
What a contractual early warning notice should contain
The specific content requirements depend on the contract form, but a properly drafted early warning notice for weather should generally address the following:
Notice particulars
A unique notice reference number, the date of issue, the project name, the contract reference, and the names and roles of the issuing and receiving parties. These administrative details establish the notice as a formal contractual communication.
The weather risk or event
A description of the forecast or actual weather conditions giving rise to the notice. Include specific parameters — rainfall, wind speed, gusts, temperature — with dates and times. Reference the forecast source or, for actual conditions, the measured data. Avoid vague language ("bad weather is forecast") in favour of specific, measurable terms.
Affected operations and impact
The trade operations or work activities that are, or are anticipated to be, affected by the weather conditions. Describe the mechanism: why do these specific conditions affect these specific operations? Reference published thresholds or manufacturer guidance where applicable. Identify the anticipated effect on the programme — which activities are delayed, and by how much.
Proposed mitigation
The steps the contractor is taking or proposing to take to minimise the impact of the weather. This may include resequencing, alternative resourcing, protective measures, or a request for the Employer's direction on how to proceed. Most contract forms require the contractor to take reasonable steps to mitigate — the notice is the opportunity to demonstrate this is happening.
Reservation of rights
A clear statement that the contractor reserves its rights to an Extension of Time and associated cost relief under the governing contract, subject to the conditions of contract and without prejudice to any other rights. This language is protective — it preserves the claim even if the full extent of the impact is not yet known.
Request for direction (where appropriate)
Where the weather conditions raise a decision that requires the Employer or Superintendent's input — whether to proceed, which activities to prioritise, whether to accelerate — a specific request for direction. Under NEC4, this may also trigger a risk reduction meeting.
Why notices are not issued — and why those reasons are costly
Site teams consistently give the same reasons for not issuing early warning notices. Every one of those reasons leads to lost entitlement.
The notice obligation is triggered by the risk of delay, not the certainty of it. Waiting until the weather arrives — or until it is clear it will affect the programme — means the notice is retrospective at best, and late at worst. The contract does not reward caution on this point.
Float is not a reason to defer notice. The purpose of an early warning notice is to give the Employer and project team the opportunity to consider mitigation while the risk is still prospective. Consuming float before issuing notice removes that opportunity and weakens the claim story when the float is exhausted.
Experienced Employers and Contract Administrators expect early warning notices on weather-exposed projects. A properly worded notice is a professional project management communication — not an accusation. The conflict risk from issuing a notice is invariably smaller than the risk of forfeited entitlement from not issuing one.
This is the most common reason and, in practical terms, the most understandable. Drafting a formal contractual notice requires specific information, careful language and time that nobody has on a pressured site. This is precisely the problem that Construction Weather's Early Warning Notice generator is built to solve.
Delivery requirements
An early warning notice that contains all the right information but is delivered by the wrong method, to the wrong person, or outside the required timeframe is not a valid contractual notice.
Before issuing any notice, confirm:
- The required delivery method. Most contracts specify written notice, and many require delivery by a specific method — email, registered post, to a nominated address, or through the project management platform. Check the contract and follow it exactly.
- The recipient. Contracts are specific about who must receive notice — the Engineer, the Superintendent, the Contract Administrator, the Project Manager. Sending it to the site representative of the Employer is not the same as sending it to the Engineer. Know the contract's requirement.
- The notice period. If the contract specifies that notice must be given within a defined number of days of the contractor becoming aware of the risk, that period begins running from the moment the contractor knew or should have known — not from the date chosen for administrative convenience.
- Proof of delivery. Keep a record of when the notice was sent and when it was received. For significant notices, request acknowledgement of receipt.
Record-keeping after the notice
Issuing the notice is the beginning of the claim process, not the end of it. After the notice is issued, the project team should:
- Record actual weather conditions daily. The notice is based on forecast conditions. The eventual EOT claim will be based on actual measured data. Both are needed — and the gap between forecast and actual is often where disputes arise.
- Record which operations were stopped or constrained. Site diaries, supervisor records and daily logs should identify the specific activities affected on each day, the reason they were affected, and the workforce and plant on site but unable to work productively.
- Maintain the programme. The EOT claim will need to show how the weather days affected the critical path. A programme that is not updated contemporaneously with weather events is much harder to use in evidence later.
- Issue further notices as the event develops. If the weather event continues or worsens beyond what the original notice described, issue follow-up notices. Do not assume one notice covers an evolving situation.
How Construction Weather generates the notice
The most common reason early warning notices are not issued is that drafting one is seen as too time-consuming and technically demanding for a site team under delivery pressure. Construction Weather is built to remove that barrier.
The notice generator
The Early Warning Notice generator in Construction Weather assembles a structured, editable draft notice using the project details, forecast conditions, affected trade operations, anticipated impact, proposed mitigation and reservation of rights. The process takes minutes.
The output is a Word document — editable, reviewable and ready for the project team to check before issue. The generator produces a draft, not a final document. The site team reviews it against the contract, confirms the factual accuracy, adjusts the wording to match the specific contract clause language, and adds any project-specific detail before issuing.
The forecast data
Construction Weather provides a 14-day trade-specific forecast, graded by operation type against published thresholds. The notice generator draws on this data to populate the weather conditions section of the notice — specific parameters, by day, for the affected operations. This removes the need for the site team to manually research and describe forecast conditions in technical terms.
Affected operations
The generator allows the site team to select the affected trade operations from the project profile. It then structures the impact description around the specific threshold conditions for those operations — why does this forecast wind speed affect crane operations? Why does this forecast rainfall affect earthworks? The generator provides the technical framing; the site team confirms it against the actual site situation.
From notice to claim
An early warning notice is the first document in the chain that leads to a properly evidenced Extension of Time claim. The notice does not make the claim — it preserves the right to make one.
The complete chain from notice to claim looks like this:
- Early warning notice — issued when forecast or actual conditions trigger the contractual obligation. Prospective, referencing forecast data and planned operations.
- Contemporaneous records — daily records of actual conditions, affected operations, programme impact and mitigation steps taken. The project diary, supervisor records and Construction Weather's advisory logs all contribute to this record.
- Historical data benchmark — the actual measured weather conditions at the project location, benchmarked against the relevant historical period to establish whether the conditions qualified under the contract's threshold (whether that is "could not reasonably have been anticipated", "occurs less frequently than once in ten years", or "exceptionally adverse").
- Programme analysis — a demonstration of how the qualifying weather days affected the critical path to completion, using the contemporaneous programme records.
- EOT claim document — the structured claim document, referencing the notice, the contemporaneous records, the weather evidence and the programme analysis.
Construction Weather supports each stage of this process — from the early warning notice through to the EOT Evidence report. The notice is the start. The evidence that follows determines whether the claim succeeds.
For a full explanation of how to build the EOT evidence from the weather data and contract clause, see the guide to proving an adverse weather extension of time claim.
Issue the notice. Preserve the entitlement.
Weather delay entitlement is not automatically preserved by the fact that the weather happened. It is preserved by doing the right things in the right order — and the first of those things is issuing a proper contractual notice at the right time.
The notice tells the Employer what is happening. It creates a contemporaneous record. It opens the conversation about mitigation while mitigation is still possible. And it protects the contractor's right to claim if the delay cannot be avoided.
Late notices lose entitlement. Missing notices lose entitlement. Vague notices that do not satisfy the contractual requirements lose entitlement. The standard form contracts are not ambiguous on this point.
The practical solution is to make issuing the notice easy enough that the site team will actually do it. Construction Weather builds the draft. The site team reviews it and issues it. The entitlement is preserved. The claim story begins at the right time.