{
  "retrieved_local_date": "2026-10-07",
  "population": "six named U.S. airport station records; not a national sample",
  "data_source": "NOAA GHCN-Daily station TMIN; missing and nonblank quality flags excluded",
  "sources": [
    {
      "station": "SEA",
      "ghcn_id": "USW00024233",
      "url": "https://www.ncei.noaa.gov/pub/data/ghcn/daily/all/USW00024233.dly",
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      "bytes": 4409100
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      "station": "BOS",
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      "url": "https://www.ncei.noaa.gov/pub/data/ghcn/daily/all/USW00014739.dly",
      "sha256": "e56f1fee603ce01a5a839935758cffb5e2e7371134c093481fe35e5f5b4a6005",
      "bytes": 5203710
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      "station": "ORD",
      "ghcn_id": "USW00094846",
      "url": "https://www.ncei.noaa.gov/pub/data/ghcn/daily/all/USW00094846.dly",
      "sha256": "e174a7d37d82ccb4d916a2d6152cbec0b7a586bb6e2700e9c92b7511eb03799a",
      "bytes": 4512780
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    {
      "station": "JFK",
      "ghcn_id": "USW00094789",
      "url": "https://www.ncei.noaa.gov/pub/data/ghcn/daily/all/USW00094789.dly",
      "sha256": "b2a122598d1144848c8d2520ffc8bf6b4c1f0a2747892e7f43a1355979d8d0c0",
      "bytes": 4246290
    },
    {
      "station": "PHX",
      "ghcn_id": "USW00023183",
      "url": "https://www.ncei.noaa.gov/pub/data/ghcn/daily/all/USW00023183.dly",
      "sha256": "1881c66dcaac668a8c6961204cbb17866a2ba93fd58864230e3bb51664113ae9",
      "bytes": 3984660
    },
    {
      "station": "SFO",
      "ghcn_id": "USW00023234",
      "url": "https://www.ncei.noaa.gov/pub/data/ghcn/daily/all/USW00023234.dly",
      "sha256": "516e2df50a90212d887637babe397c94f6e02ac2e73662a69d0b5adb55354c7c",
      "bytes": 4162050
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  ],
  "method_parameters": {
    "first_winter_ending_year": 1961,
    "last_winter_ending_year": 2026,
    "reference_ending_years": [
      1991,
      2020
    ],
    "max_month_missing": 2,
    "max_winter_missing": 4,
    "min_coverage_pass_winters": 60,
    "required_reference_winters": 30
  },
  "station_history_sources": [
    {
      "sha256": "7d3b3f170123a2e193abd59eb6eabfebc0a1b0f76161989720f9975411aae138",
      "url": "https://www.ncei.noaa.gov/access/homr/services/station/search?qid=GHCND%3AUSW00024233&date=all",
      "returned_station_records": 1,
      "selected_ncdc_station_id": "20027732",
      "selection": "current ICAO identifier matches station-candidates.csv; retain all returned records",
      "station": "SEA"
    },
    {
      "sha256": "b6b700fb7e2fcec47942beb635cc337f9cb4759d65a4b86673e18168f498218b",
      "url": "https://www.ncei.noaa.gov/access/homr/services/station/search?qid=GHCND%3AUSW00014739&date=all",
      "returned_station_records": 1,
      "selected_ncdc_station_id": "20009288",
      "selection": "current ICAO identifier matches station-candidates.csv; retain all returned records",
      "station": "BOS"
    },
    {
      "sha256": "eda446cd0f9c70fc905b9170fecd30bf034a77e2bb3d51f99f3c5843faf53174",
      "url": "https://www.ncei.noaa.gov/access/homr/services/station/search?qid=GHCND%3AUSW00094846&date=all",
      "returned_station_records": 1,
      "selected_ncdc_station_id": "10003214",
      "selection": "current ICAO identifier matches station-candidates.csv; retain all returned records",
      "station": "ORD"
    },
    {
      "sha256": "db3c006a086c837b0c367bc3e4c7c66dd74c73a3fb97fabb0f55ba05f3487dc6",
      "url": "https://www.ncei.noaa.gov/access/homr/services/station/search?qid=GHCND%3AUSW00094789&date=all",
      "returned_station_records": 2,
      "selected_ncdc_station_id": "20019418",
      "selection": "current ICAO identifier matches station-candidates.csv; retain all returned records",
      "station": "JFK"
    },
    {
      "sha256": "39dcbed5ed6f4e2db5ea8e8a916ce3fc4ac6a2bdc6dce366928f092e30ef4101",
      "url": "https://www.ncei.noaa.gov/access/homr/services/station/search?qid=GHCND%3AUSW00023183&date=all",
      "returned_station_records": 1,
      "selected_ncdc_station_id": "20001019",
      "selection": "current ICAO identifier matches station-candidates.csv; retain all returned records",
      "station": "PHX"
    },
    {
      "sha256": "df69d34afbc3133993347a588a8463975132fe8268a3f0ed58848647d8aa112e",
      "url": "https://www.ncei.noaa.gov/access/homr/services/station/search?qid=GHCND%3AUSW00023234&date=all",
      "returned_station_records": 1,
      "selected_ncdc_station_id": "10001448",
      "selection": "current ICAO identifier matches station-candidates.csv; retain all returned records",
      "station": "SFO"
    }
  ],
  "generator": "about/scripts/make_winter_station_plots.py",
  "limitations": [
    "No adjustment for station moves, equipment, observation practice or urbanization is applied.",
    "Two JFK internal-consistency-flagged days are excluded; their winters remain within the declared coverage limits.",
    "Thirty winter-ending years 1991\u20132020 span December 1990\u2013February 2020, not calendar-year DJF sampling.",
    "This is a calculated reference, not the official NOAA Climate Normal.",
    "A quality-flag screen cannot establish attribution or remove every plausible observation error."
  ],
  "files": {
    "airport-winter-daily-inputs.csv": "259fd566a230ea52c9b0d3936fc20c87f5f071d9046dac41565b79fba696f212",
    "airport-winter-monthly-inputs.csv": "bce456689501a00668c7073eb6ba114957a87d5ebbc04f1e0cd8519560334880",
    "airport-winter-series.csv": "88d4c4f7df17af133b20032516953e583b83dfc09306bda8ece3ed994089e4bf",
    "airport-winter-summary.csv": "d2d796c1475bc2136a2bf8261e09fa5afb25ebba7eee6f0de2473327eb4b8823",
    "airport-winter-excluded-readings.csv": "20e33eb7b4b2fbedf640c80afc980d5c05773da8e0910732eb1bbce7b8d5cf3f",
    "airport-winter-recorded-relocations.csv": "631f4cdb75c5a5267f8684fbabdb77fa5b727de36f2025d3d88d2d2c23479b02"
  }
}