Weather days in the baseline: how many, where they go and the monthly reconciliation
Rain interrupts an exterior activity, and the monthly meeting asks how much weather the baseline allowed. The scheduler says it was included in durations. The superintendent has a weather diary, but nobody can connect those entries to the allowance.
State the weather-planning assumption behind the baseline and show where it is included. Environment and Climate Change Canada’s climate normals describe average climatic conditions; they are background information, not a forecast for your work dates. Combine relevant local information with the actual activity conditions and the project’s requirements. Keep observed weather, work interruption and any contractual treatment separate so the record does not turn a planning assumption into an entitlement claim.
Make the allowance traceable
- Identify weather-sensitive work. Review the sequence with the responsible leads and record which activities depend on particular working or installation conditions. Confirm those requirements from the applicable project information rather than guessing a universal temperature or rainfall threshold.
- Choose relevant background information. Check the location, period and coverage of the public climate information used. Explain its limitations for this site and work phase, including assumptions that the data cannot settle.
- Agree a planning method. Discuss how the team will translate that information and activity exposure into a project assumption. Record the reasoning, uncertainty and responsible review rather than converting every wet calendar day into a lost construction day.
- Represent the allowance once. Use the agreed calendar, a visible weather activity or stated allowance within durations, as appropriate to the project’s scheduling requirements. Explain the method in the narrative and check that overlapping approaches do not count the same time twice.
- Keep observations connected to work. Record the date, location, observed condition, activity affected and actual response. Distinguish no work planned, work continuing elsewhere and work genuinely interrupted instead of marking every weather entry as delay.
- Reconcile consistently. Compare allowance and recorded interruption for the same period and activity basis at the monthly review. Explain differences and revise forecasts through the agreed process, preserving the original baseline and any contractual notices separately.
Common mistakes
- Describing climate averages as a forecast for the project.
- Counting an allowance both in durations and in a separate activity.
- Equating a weather observation with an automatic entitlement to extra time.
Checklist
A weather allowance you can explain
- Sensitive activities and confirmed conditions are listed.
- Background information and limitations are identified.
- The planning method and uncertainty are stated.
- The allowance appears once in the programme.
- Observed disruption is reconciled on the same basis.
Check your understanding
The diary records rain, but the affected activity was not scheduled that day. Should the entry consume its allowance?
