When weather disrupts a construction schedule, the contract usually entitles the contractor to a time extension. But claiming a weather delay and proving a weather delay are two different things. Project owners, general contractors, and construction attorneys evaluate weather delay claims based on documentation, and the quality of that documentation often plays a major role in whether the extension is granted or disputed.
This guide covers the practical workflow for documenting weather delays: what to record, when to record it, what data sources to reference, and how to present the documentation in a format that aligns with typical contract requirements.
What Construction Contracts Require
Most commercial construction contracts include weather delay provisions, though the specific language varies. AIA, ConsensusDocs, and EJCDC standard forms each address weather differently, but the general framework is similar.
Excusable delay provisions
Typically allow time extensions for weather that is "unusually severe" or that exceeds historically normal conditions for the project location and time of year. The key word is "unusual." Routine rain in Seattle in November is not an excusable delay. A week of continuous rainfall that exceeds the historical average by a significant margin may be.
Notice requirements
Specify how quickly the contractor must notify the project owner of a weather delay. Many contracts require written notice within 3 to 7 days of the delay event. Missing this window can forfeit the right to claim the extension, regardless of how severe the weather was.
Documentation requirements
Vary but generally expect the contractor to maintain contemporaneous records showing the weather conditions that prevented work, the specific activities that were delayed, and the impact on the critical path schedule.
Threshold definitions
Some contracts specify measurable criteria: precipitation exceeding a certain amount (often 0.5 inches), wind speeds above a threshold (often 30 to 40 mph), or temperatures below a minimum for specific activities (often 32 degrees Fahrenheit for concrete work).
Understanding your contract's specific provisions is the starting point for building a defensible weather delay claim.
The Daily Documentation Workflow
Effective weather delay documentation happens daily, not retroactively. Reconstructing weather records weeks or months after the fact is more expensive, less credible, and more likely to face challenges.
Maintain a daily weather log
Record the general conditions each day: precipitation (type and approximate amount), wind conditions, temperature range, and any conditions that prevented or limited work. Note the specific hours when work was suspended and the reason.
Cross-reference with archived observation data
Your site log records subjective observations ("heavy rain this morning, crew stood down until noon"). Archived weather data from the nearest ASOS or AWOS station provides objective measurements (0.87 inches of precipitation recorded between 6 AM and 11 AM, wind gusts to 34 mph). The site log and the weather data should tell the same story.
Document the impact on scheduled activities
A weather delay claim requires showing that the weather prevented specific work activities. "Rain prevented earthwork operations" is stronger than "weather delay." Identify the activities on the critical path that were affected and explain why those activities could not proceed under the recorded conditions.
Photograph conditions when relevant
Standing water on a grading site, snow-covered work areas, or wind conditions that made crane operations unsafe provide visual documentation that supports the written record.
Aligning Weather Data with Contract Thresholds
If your contract defines specific thresholds for excusable weather, your documentation should explicitly map the recorded conditions against those thresholds.
Contract specifies measurable criteria
If the contract defines an excusable weather day as one with precipitation exceeding 0.5 inches, your documentation should show the historical weather report for each claimed day, highlighting the recorded precipitation total relative to the 0.5-inch threshold.
Common defined thresholds include precipitation above 0.5 inches, sustained wind above 30 to 40 mph, or temperatures below 32 degrees Fahrenheit for concrete work.
Contract uses general language
If the contract references "unusually severe" weather without defining specific thresholds, compare the recorded conditions against historical averages for the project location during the same time of year.
If the contract period experienced 15 rain days in March when the historical average is 8, the excess represents the unusually severe weather that supports the extension request.
How to Present Weather Delay Documentation
The format of your weather delay documentation affects how it is received. A disorganized pile of daily logs and weather printouts creates work for the reviewer and invites challenges. A structured presentation is more persuasive.
Organize by date
Each claimed delay day should have its own entry showing the date, the recorded weather conditions (temperature range, precipitation, wind, visibility), the contract threshold it exceeded, the activities affected, and the schedule impact.
Include the data source
Identify the weather observation station used, its distance from the project site, and the data source (archived NOAA and NWS observation records). This establishes credibility and allows the reviewer to independently confirm the data.
Summarize the totals
After presenting the individual days, summarize the total number of delay days claimed, organized by category if applicable (rain days, wind days, temperature days). Compare against the contract's weather allowance if one exists.
Reference the critical path
Show how the delay days affected the project's critical path schedule. Weather delays to non-critical activities generally do not support a time extension, so the documentation should focus on activities that determined the project completion date.
Common Weather Delay Documentation Mistakes
Several common mistakes weaken weather delay claims.
Retroactive documentation
Preparing weather delay documentation months after the fact rather than contemporaneously. Courts and arbitrators give more weight to records created at or near the time of the event.
Relying only on site logs without objective data
A superintendent's log entry saying "rained all day" is subjective. Pairing it with archived observation data showing 1.2 inches of precipitation recorded at the nearest station makes it objective and independently reviewable.
Failing to provide timely notice
Many contracts require notice within days of the delay event. A weather delay claim submitted at the end of the project for delays that occurred months earlier may be contractually barred.
Claiming every rain day
Not every day with precipitation is an excusable delay day. Light rain that does not prevent the scheduled work activity, or rain that falls outside working hours, generally does not qualify. Over-claiming undermines credibility and invites scrutiny of the entire claim.
Ignoring the critical path
Claiming weather delays for activities that have float (are not on the critical path) does not support a time extension. The documentation must connect the weather delay to the project's controlling schedule.
Frequently Asked Questions
The definition depends on your contract. Most contracts require weather conditions that are "unusually severe" or that exceed defined thresholds (such as precipitation over 0.5 inches or temperatures below 32 degrees) and that prevented specific work activities on the critical path.
Maintain daily site logs recording conditions and work impacts. Supplement with archived weather observation data from the nearest monitoring station showing measured conditions. Map each claimed day against your contract's threshold definitions.
Archived surface observations from ASOS and AWOS stations provide hourly temperature, precipitation, wind, and visibility data. NWS alerts document periods when hazardous conditions were present. NCEI storm event records document significant weather events at the county level. For a detailed comparison of data sources, see Historical Weather Records: Cost Comparison.
Archived weather data is available for past dates, so the observation records can be retrieved at any time. However, site logs and impact documentation are more credible when created contemporaneously. The best practice is to maintain daily records during the project and supplement them with archived weather data.
This varies significantly by location and season. Many contracts include a weather day allowance based on historical averages for the project location. Days exceeding this allowance may qualify as excusable delays. Comparing your project's actual weather against historical averages for the same location and time period provides the basis for this analysis.
For most construction delay claims, structured weather documentation showing daily conditions and their alignment with contract thresholds is sufficient. A forensic meteorologist may be appropriate if the claim involves substantial liquidated damages, if the weather conditions are disputed, or if the claim is heading to arbitration or litigation.
The Bottom Line
Construction weather delay documentation is a daily practice, not a one-time exercise. The contractors who successfully claim weather delays are the ones who maintain contemporaneous records, cross-reference their site logs with objective weather data, provide timely contractual notice, and connect the weather impacts to the critical path schedule.
Archived weather observation data provides the objective foundation for every delay claim. It records what actually happened at the nearest monitoring station, hour by hour, and it does not change over time. The recorded conditions remain permanently available as an objective record of the weather on that date.
This article is provided for informational purposes only and does not constitute legal or contractual advice. Contract provisions and documentation requirements vary by agreement.
StormRecord articles are prepared using archived U.S. government weather data and reviewed for technical accuracy by a degreed meteorologist.
StormRecord does not provide legal or contractual advice. Contract provisions and documentation requirements vary by agreement.