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Weather Delay Days in Indianapolis, IN

A 2016-2025 NOAA station baseline for Indianapolis, IN, scored against Silt soil. January is the worst month at roughly 16 unworkable workdays for earthwork, grading and foundation work; the full monthly baseline is below. Enclosed and vertical work is not modelled.

Month by month

Typical is the ten-year mean — the figure to carry in a bid or schedule. Median is the middle year of the ten; where it exceeds the mean, the baseline is skewed by unusually dry years. Abnormal above is the mean plus one standard deviation, past which a month sits outside its normal range and is the stronger basis for a claim.

Month Avg rainfall Typical lost workdays Median Abnormal above
January 3.09″ 16 17 19
February 2.86″ 12 14 16
March 4.48″ 13 12 17
April 5.11″ 13 13 16
May 5.21″ 13 15 19
June 4.83″ 9 9 13
July 5.66″ 11 12 15
August 3.77″ 9 10 13
September 2.67″ 6 5 10
October 3.17″ 7 5 13
November 2.81″ 12 13 15
December 2.34″ 13 14 17

What these numbers mean

A workday counts as lost when precipitation exceeded 0.1″, or the ground had not finished drying from an earlier rain, or the ground was frozen. Only Monday to Friday is counted. Days the station did not report are excluded from the count entirely rather than assumed workable — understating a contractor’s exposure is the one direction of error a delay figure must never make.

Read these month by month, not added up. Each row is an independent baseline for a site in the condition it is in that month. Summing twelve of them would assume a jobsite never improves — no stone haul roads, no stabilised pads, no ditching — which is wrong for any real project past its first few months. Over a single month, or over the two-to-four week window a delay claim actually covers, that effect is negligible and these figures hold. Over a year it is not, so no annual total is published here.

On silt soil this model charges an average of 1.35 drying days per rain day in Indianapolis, IN. That is the figure worth checking against your own experience: if it is wrong for your sites, every number on this page moves with it.

Why Silt soil matters here

Rainfall totals alone understate an earthwork schedule, because the ground stays untrafficable after the rain stops. The drying clock for Indianapolis, IN is seeded at Silt, 2.0 base drying day(s), then adjusted for the day’s temperature, rainfall intensity, and how wet the ground already was over the preceding five days.

The same month of rain costs a sand site almost nothing and a clay site a week. That is why two contractors in the same county can honestly disagree about how many weather days a job should carry.

Year by year: January

An average hides the spread, and the spread is what a claim turns on. Lost workdays in January for each year of the baseline:

YearLost workdays
2016 15
2017 15
2018 18
2019 19
2020 16
2021 11
2022 18
2023 14
2024 18
2025 18

Nearby metros

Soil changes faster than weather does. These are the closest markets we track — note how the worst month can differ even where the rainfall barely does.

MetroDistanceSoilWorst monthLost workdays
Chicago, IL 165 mi Clay January 19
Columbus, OH 168 mi Silt January 17
St. Louis, MO 230 mi Silt January 13
Detroit, MI 240 mi Clay January 19
Milwaukee, WI 243 mi Silt January 18

See every metro we track →

Download this data

The full baseline for Indianapolis, IN — every month, every individual year, with the station and soil basis attached — is available as JSON under a CC BY 4.0 licence. Use it, cite it.

Download Indianapolis, IN JSON

Data source

Observations from the NOAA National Centers for Environmental Information, Global Historical Climatology Network – Daily (GHCND) — U.S. Government public-domain station records. Baseline 2016-2025, 3653 observed days. Algorithm v2.3.0, generated August 23, 2026.

Citing this page

Published under CC BY 4.0. Free to quote, republish or build on, including commercially, provided the attribution below travels with it.

Ilystics LLC. Construction weather delay days — Indianapolis, IN (2016–2025). Ilystics Weather Delay Index, v2.3.0. Retrieved from https://ilystics.com/weather-delay-days/indianapolis-in

Need this for your actual jobsite?

A metro average is a planning figure. Enter your ZIP and dates and the estimator runs the same model against the station nearest your site, on your soil, and returns a contract-ready exhibit. Free, no account.

Run it for your ZIP

These figures model soil-dependent site work — earthwork, grading, excavation, foundations and underground utilities. Enclosed and vertical work is not modelled. They are planning figures derived from station observations and a deterministic soil model, not site-specific geotechnical findings, and they do not establish contractual entitlement, causation or damages.

Frequently asked questions

Which month costs a Indianapolis, IN jobsite the most workdays?

January, at roughly 16 unworkable workdays across the 2016-2025 NOAA baseline for soil-dependent site work on Silt soil. Winter months often rank worse than wetter summer ones because frontal rain arrives spread out, and each event collects its own drying tail, where summer storms cluster and their tails overlap.

How many weather delay days should I budget for a bid in Indianapolis, IN?

Between about 6 lost workdays in September and 16 in January, on Silt soil across the 2016-2025 NOAA baseline. Budget month by month against the months you will actually be in the ground rather than from an annual figure: these monthly baselines are independent, and adding them together assumes a site never improves over a year, when stone haul roads, stabilised pads and ditching all go in over the first months of a job.

What is the best month for excavation in Indianapolis, IN?

September, at roughly 6 lost workdays against 16 in January — a difference of about 10 workdays between the easiest and hardest months of the year. Moving a soil-dependent package across that gap changes a schedule more than most weather contingencies allow for.

What counts as an abnormal weather month in Indianapolis, IN?

In January, anything beyond about 19 lost workdays, against a typical 16. That threshold is the ten-year mean plus one standard deviation, which places the month among the worst years on record for this metro. It is an Ilystics convention for putting a number on the contractual phrase "abnormal" or "unusually severe" — no court or contract has adopted it, and the per-year figures are published alongside so the line can be checked or argued with.

How long does soil take to dry after rain in Indianapolis, IN?

Sites here are scored against Silt soil, with a base drying time of 2 days after a meaningful rain. Averaged across the year, each rain day in Indianapolis, IN carries roughly 1.35 further days before the ground is trafficable again. That drying tail, not the rainfall itself, is usually the larger half of a weather delay and the half that goes undocumented.

What counts as a lost workday?

A Monday-to-Friday day on which precipitation exceeded 0.1 inch, or the ground had not finished drying from earlier rain, or the ground was frozen. Weekends are excluded, and days with no station reading are excluded rather than assumed workable.

Does this apply to all construction in Indianapolis, IN?

No. These figures model soil-dependent site work - earthwork, grading, excavation, foundations and underground utilities. Enclosed and vertical work is largely unaffected by the conditions modelled here.

Related guides

Why the wettest month isn't the worst month Weather delay days for every metro we track How to calculate anticipated weather days for a bid How long soil takes to dry after rain, by type