JCT Adverse Weather Extensions of Time
Objective weather evidence for JCT extensions of time claims. Automated data collection, historical comparison, and activity impact analysis. Demonstrate that conditions were genuinely exceptional.
Understanding JCT Adverse Weather Claims
Under JCT contracts (Clause 2.26.9), contractors can claim extensions of time when "exceptionally adverse weather conditions" prevent progress on the works. Unlike NEC4, JCT does not prescribe a specific statistical test — the contractor must demonstrate that conditions were genuinely exceptional for the time of year and location.
This makes objective, historical weather data essential. Without a clear statistical comparison, claims often fail because the contractor cannot prove that conditions went beyond what should reasonably have been expected and planned for.
What Counts as Exceptionally Adverse Weather
The JCT test requires demonstrating that weather was significantly worse than would reasonably be expected. Objective data is essential.
Prolonged Heavy Rainfall
Extended periods of rainfall that significantly exceed historical averages for the location and time of year, preventing earthworks, concreting, or other weather-sensitive activities.
Sustained High Winds
Wind speeds that exceed safe working limits for crane operations, scaffolding, and other height-dependent activities over a period that goes beyond normal seasonal variation.
Extreme Cold and Frost
Prolonged freezing conditions or unexpected late frost events that prevent concrete pours, bricklaying, or other temperature-sensitive construction activities.
Exceptional Snowfall
Snow accumulation or blizzard conditions that go beyond seasonal norms, causing site shutdowns and access restrictions that could not reasonably have been anticipated.
Combined Severe Conditions
Combinations of adverse weather — such as wind and rain together — that individually might be manageable but collectively prevent safe or effective working.
Flooding and Waterlogging
Site flooding or ground conditions rendered unworkable by accumulated rainfall, where the duration and intensity exceeded what would normally be expected.
How WeatherWise Supports JCT Claims
Building the objective evidence that JCT adverse weather claims require.
Automated Recording
Continuous weather data capture at your site from project start. Builds the contemporaneous record that JCT claims depend on.
Historical Comparison
Compares actual conditions against 45+ years of historical data to demonstrate that weather was genuinely exceptional for the time and place.
Activity Impact Analysis
Links weather events to specific activities in your programme, demonstrating which works were affected and how the critical path was impacted.
Evidence Packages
Generate professional PDF evidence reports formatted for JCT claims, including daily records, statistical analysis, and activity impact assessment.
Evidence Requirements for JCT Extensions of Time
The key evidence elements needed to support a JCT adverse weather claim.
Proof of Exceptional Conditions
Objective data demonstrating that weather was significantly worse than would reasonably be expected. WeatherWise provides the statistical comparison against 45+ years of historical data.
Impact on Progress
Demonstration that adverse weather actually prevented or delayed progress on the works. WeatherWise links weather conditions to activity-specific thresholds and critical path impact.
Contemporaneous Records
Records captured at the time the weather occurred, not compiled retrospectively. WeatherWise records automatically every day, creating an unbroken evidence trail.
Timely Notification
JCT requires prompt notification of delay events. WeatherWise alerts flag adverse conditions as they occur, supporting timely notification compliance.
Historical Context
Comparison data showing where actual conditions fall relative to the historical distribution. WeatherWise uses 45+ years of ERA-5 data for robust statistical context.
Professional Evidence Reports
Clear, auditable PDF reports with data visualisation and statistical analysis, formatted for use in JCT extension of time applications.
Frequently Asked Questions
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What makes weather "exceptionally adverse" under JCT?▾
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