{
    "dataset": "Ilystics weather delay days \u2014 Chicago, IL",
    "landingPage": "https://ilystics.com/weather-delay-days/chicago-il",
    "license": "https://creativecommons.org/licenses/by/4.0/",
    "attribution": "Ilystics LLC, https://ilystics.com",
    "sourceData": "NOAA NCEI Global Historical Climatology Network - Daily (GHCND), U.S. Government public domain",
    "algorithmVersion": "v2.3.0",
    "generatedAt": "2026-08-23T17:13:03+00:00",
    "baseline": {
        "startYear": 2016,
        "endYear": 2025,
        "observedDays": 3645
    },
    "location": {
        "metro": "Chicago",
        "state": "IL",
        "lat": 41.8781,
        "lng": -87.6298
    },
    "soilBasis": {
        "effectiveSoil": "clay",
        "baseDryingDays": 3,
        "label": "Clay, 3.0 base drying day(s)"
    },
    "station": [],
    "scope": "Soil-dependent site work only: earthwork, grading, excavation, foundations and underground utilities. Enclosed and vertical construction is not modelled.",
    "readMe": "Monthly figures are independent baselines and must not be summed into an annual total: doing so assumes a jobsite never improves over a year. See https://ilystics.com/weather-delay-days for the full explanation.",
    "months": [
        {
            "month": 1,
            "monthName": "January",
            "avgPrecipInches": 1.46,
            "lostWorkdaysMean": 19,
            "lostWorkdaysMedian": 19,
            "abnormalThreshold": 21,
            "dryingDaysPerRainDay": 2.86,
            "workdayCoveragePct": 100,
            "lostWorkdaysByYear": {
                "2016": 15,
                "2017": 18,
                "2018": 21,
                "2019": 22,
                "2020": 17,
                "2021": 20,
                "2022": 20,
                "2023": 15,
                "2024": 17,
                "2025": 21
            }
        },
        {
            "month": 2,
            "monthName": "February",
            "avgPrecipInches": 1.77,
            "lostWorkdaysMean": 14,
            "lostWorkdaysMedian": 13,
            "abnormalThreshold": 18,
            "dryingDaysPerRainDay": 1.64,
            "workdayCoveragePct": 99,
            "lostWorkdaysByYear": {
                "2016": 12.1,
                "2017": 13.1,
                "2018": 19.2,
                "2019": 19.2,
                "2020": 13.1,
                "2021": 13.1,
                "2022": 18.2,
                "2023": 15.2,
                "2024": 8.1,
                "2025": 11.1
            }
        },
        {
            "month": 3,
            "monthName": "March",
            "avgPrecipInches": 2.74,
            "lostWorkdaysMean": 13,
            "lostWorkdaysMedian": 14,
            "abnormalThreshold": 18,
            "dryingDaysPerRainDay": 1.91,
            "workdayCoveragePct": 99.5,
            "lostWorkdaysByYear": {
                "2016": 11,
                "2017": 18.1,
                "2018": 7,
                "2019": 13.1,
                "2020": 13.1,
                "2021": 7,
                "2022": 14.1,
                "2023": 21.1,
                "2024": 14.1,
                "2025": 14.1
            }
        },
        {
            "month": 4,
            "monthName": "April",
            "avgPrecipInches": 3.51,
            "lostWorkdaysMean": 12,
            "lostWorkdaysMedian": 14,
            "abnormalThreshold": 16,
            "dryingDaysPerRainDay": 1.55,
            "workdayCoveragePct": 100,
            "lostWorkdaysByYear": {
                "2016": 16,
                "2017": 15,
                "2018": 5,
                "2019": 16,
                "2020": 13,
                "2021": 6,
                "2022": 16,
                "2023": 9,
                "2024": 10,
                "2025": 14
            }
        },
        {
            "month": 5,
            "monthName": "May",
            "avgPrecipInches": 4.03,
            "lostWorkdaysMean": 14,
            "lostWorkdaysMedian": 17,
            "abnormalThreshold": 19,
            "dryingDaysPerRainDay": 1.44,
            "workdayCoveragePct": 99.6,
            "lostWorkdaysByYear": {
                "2016": 18.1,
                "2017": 18.1,
                "2018": 12.1,
                "2019": 18.1,
                "2020": 17.1,
                "2021": 10,
                "2022": 16.1,
                "2023": 3,
                "2024": 17.1,
                "2025": 10
            }
        },
        {
            "month": 6,
            "monthName": "June",
            "avgPrecipInches": 3.74,
            "lostWorkdaysMean": 11,
            "lostWorkdaysMedian": 12,
            "abnormalThreshold": 14,
            "dryingDaysPerRainDay": 1.76,
            "workdayCoveragePct": 100,
            "lostWorkdaysByYear": {
                "2016": 12,
                "2017": 11,
                "2018": 13,
                "2019": 16,
                "2020": 9,
                "2021": 7,
                "2022": 6,
                "2023": 5,
                "2024": 12,
                "2025": 14
            }
        },
        {
            "month": 7,
            "monthName": "July",
            "avgPrecipInches": 5.11,
            "lostWorkdaysMean": 12,
            "lostWorkdaysMedian": 13,
            "abnormalThreshold": 15,
            "dryingDaysPerRainDay": 2,
            "workdayCoveragePct": 100,
            "lostWorkdaysByYear": {
                "2016": 15,
                "2017": 10,
                "2018": 6,
                "2019": 15,
                "2020": 11,
                "2021": 7,
                "2022": 14,
                "2023": 14,
                "2024": 16,
                "2025": 12
            }
        },
        {
            "month": 8,
            "monthName": "August",
            "avgPrecipInches": 3.09,
            "lostWorkdaysMean": 9,
            "lostWorkdaysMedian": 9,
            "abnormalThreshold": 13,
            "dryingDaysPerRainDay": 1.65,
            "workdayCoveragePct": 99.6,
            "lostWorkdaysByYear": {
                "2016": 14.1,
                "2017": 5,
                "2018": 10,
                "2019": 16.1,
                "2020": 3,
                "2021": 9,
                "2022": 8,
                "2023": 8,
                "2024": 9,
                "2025": 8
            }
        },
        {
            "month": 9,
            "monthName": "September",
            "avgPrecipInches": 2.31,
            "lostWorkdaysMean": 7,
            "lostWorkdaysMedian": 7,
            "abnormalThreshold": 12,
            "dryingDaysPerRainDay": 1.8,
            "workdayCoveragePct": 100,
            "lostWorkdaysByYear": {
                "2016": 5,
                "2017": 1,
                "2018": 9,
                "2019": 13,
                "2020": 13,
                "2021": 5,
                "2022": 7,
                "2023": 11,
                "2024": 6,
                "2025": 0
            }
        },
        {
            "month": 10,
            "monthName": "October",
            "avgPrecipInches": 4.57,
            "lostWorkdaysMean": 12,
            "lostWorkdaysMedian": 13,
            "abnormalThreshold": 15,
            "dryingDaysPerRainDay": 1.47,
            "workdayCoveragePct": 100,
            "lostWorkdaysByYear": {
                "2016": 14,
                "2017": 16,
                "2018": 13,
                "2019": 11,
                "2020": 15,
                "2021": 12,
                "2022": 7,
                "2023": 13,
                "2024": 5,
                "2025": 10
            }
        },
        {
            "month": 11,
            "monthName": "November",
            "avgPrecipInches": 1.63,
            "lostWorkdaysMean": 11,
            "lostWorkdaysMedian": 11,
            "abnormalThreshold": 15,
            "dryingDaysPerRainDay": 2.68,
            "workdayCoveragePct": 100,
            "lostWorkdaysByYear": {
                "2016": 11,
                "2017": 13,
                "2018": 18,
                "2019": 14,
                "2020": 10,
                "2021": 10,
                "2022": 7,
                "2023": 9,
                "2024": 13,
                "2025": 9
            }
        },
        {
            "month": 12,
            "monthName": "December",
            "avgPrecipInches": 1.72,
            "lostWorkdaysMean": 14,
            "lostWorkdaysMedian": 14,
            "abnormalThreshold": 17,
            "dryingDaysPerRainDay": 3.13,
            "workdayCoveragePct": 100,
            "lostWorkdaysByYear": {
                "2016": 18,
                "2017": 9,
                "2018": 11,
                "2019": 15,
                "2020": 11,
                "2021": 14,
                "2022": 16,
                "2023": 14,
                "2024": 14,
                "2025": 19
            }
        }
    ]
}