Free tool
What a rained out morning actually costs
Enter your crew size, burdened rate, idle equipment and daily general conditions to see the real cost of a weather day and of every weather day you failed to document.
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How many calendar days are you actually owed
Put your baseline allowance next to the qualifying days you logged, add the dry out days that followed, and see the extension you should request and how much of it late notice puts at risk.
Almost every commercial contract anticipates some adverse weather. The clause either publishes a monthly table of expected weather days or points at climate normals for a named station. Days inside that allowance are yours to absorb. Days beyond it are the ones that support a time extension, and often the ones that support extended general conditions as well. Contractors lose this argument by never doing the subtraction until the job is nearly over.
This estimator does the subtraction while you can still act on it. It also handles the piece most schedules ignore: the dry out days that follow a rain event on earthwork and site utilities, when the gauge reads zero but saturated subgrade still keeps equipment off the pad. Finally it shows how many of your excess days are exposed because notice went out later than the contract window allows, which is the most common reason an otherwise valid day gets struck.
Your result
Dry out days to add
12
Days when the rain had stopped but saturated ground still kept equipment off the work.
Total weather impacted days
43
Qualifying rain days plus the dry out days that followed them.
Calendar days beyond the baseline
21
The days above your contract allowance that support a time extension request.
Days exposed by late notice
5
A rough share of your excess days that a reviewer could strike on timeliness alone.
Treat this as a monthly check on where you stand, not as the extension request itself, which needs the day by day record behind every number.
The baseline is negotiable before you sign and fixed after
When an owner publishes a monthly weather day table, that table decides how many days you absorb for free. A table built from a station forty miles inland can badly understate a coastal site, and a table that assigns two days to a Gulf Coast June is not describing the same June your crews will work. Once the contract is executed, that argument is closed and the subtraction above is all you have.
That is why the baseline belongs in preconstruction. Build your own table from published climate normals for the station the contract names, compare it against what the owner proposed, and put the difference in writing before signature. The estimator then becomes a monthly scorecard rather than a year end surprise.
Dry out days are the ones most teams never claim
Set the dry out ratio to zero and watch your extension collapse. On earthwork, underground utilities and site concrete, the day after a heavy rain is frequently a total loss even under clear skies, because a saturated subgrade will not hold a scraper or pass a proof roll. The gauge shows nothing, so the day never enters the record.
Claiming those days requires the same discipline as the rain day itself: the moisture condition, standing water photographs, the geotechnical or superintendent call not to proceed, and the crew and equipment hours lost while the site drained. Record them the same morning and they hold. Reconstruct them in a claim narrative months later and they usually do not.
Questions about this calculator
What counts as a qualifying weather day?
Your contract defines it, usually as measured precipitation above a threshold, or temperature outside a stated range, at a named source. Most clauses also require that the weather actually stopped work on a controlling activity. Both parts have to be true and both have to be recorded.
Is a dry out day claimable at all?
It depends entirely on your clause and how well it is documented. Many standard clauses cover the effects of adverse weather rather than only the precipitation event itself, which supports a dry out day. It stands or falls on the site condition evidence you captured that morning.
Why does late notice reduce my days?
Most weather clauses require written notice within a set number of days of the event, and a day noticed after that window gives a reviewer a clean procedural reason to strike it without arguing the weather. The exposure figure here is a rough indicator, not a legal opinion. Ask your counsel about your specific clause.
More free tools and working documents
Working document
The weather day log and notice template
A one page fill in record for the morning it rains, built so a reviewer who was never on your site can follow the day from the first gauge reading to the notice that went out.
Turn that figure into a day that survives review
What you have above is your own estimate multiplied out, which is enough for the next owner meeting and not enough for a claim. The version that holds up carries the measured amount, the source and reading time, the activities that could not proceed, the idle equipment hours and the notice trail. Book a walkthrough and we will stand up one site with your contract threshold, your named station and your monthly day table, so tomorrow's weather day starts documented.