{
 "slug": "detroit-mi",
 "place": {
  "name": "Detroit",
  "state": "MI",
  "census_name": "Detroit city",
  "census_geoid": "2622000",
  "lat": 42.38304,
  "lon": -83.10224,
  "station_distance_km": 25.3
 },
 "station": {
  "id": "USW00094847",
  "name": "DETROIT METRO AP, MI US",
  "lat": 42.2314,
  "lon": -83.3308,
  "elevation_m": 192.3,
  "elevation_ft": 631,
  "source_urls": {
   "monthly": "https://www.ncei.noaa.gov/data/normals-monthly/1991-2020/access/USW00094847.csv",
   "annual": "https://www.ncei.noaa.gov/data/normals-annualseasonal/1991-2020/access/USW00094847.csv"
  }
 },
 "period": "1991-2020",
 "units": {
  "temperature": "F",
  "precipitation": "in",
  "snowfall": "in",
  "days": "days",
  "dates": "MM-DD",
  "prob_low_le_32f_pct": "percent"
 },
 "months": [
  {
   "month": 1,
   "name": "January",
   "high_f": 32.3,
   "low_f": 19.2,
   "mean_f": 25.8,
   "precip_in": 2.23,
   "snow_in": 14.0,
   "days_precip_ge_0_01in": 13.4,
   "days_precip_ge_0_10in": 5.9,
   "days_snow_ge_1_0in": 4.3,
   "days_high_ge_90f": 0.0,
   "days_high_le_32f": 16.0,
   "days_low_le_32f": 27.2,
   "prob_low_le_32f_pct": 100.0
  },
  {
   "month": 2,
   "name": "February",
   "high_f": 35.2,
   "low_f": 20.8,
   "mean_f": 28.0,
   "precip_in": 2.08,
   "snow_in": 12.5,
   "days_precip_ge_0_01in": 11.0,
   "days_precip_ge_0_10in": 5.3,
   "days_snow_ge_1_0in": 3.6,
   "days_high_ge_90f": 0.0,
   "days_high_le_32f": 11.6,
   "days_low_le_32f": 25.1,
   "prob_low_le_32f_pct": 100.0
  },
  {
   "month": 3,
   "name": "March",
   "high_f": 45.9,
   "low_f": 28.6,
   "mean_f": 37.2,
   "precip_in": 2.43,
   "snow_in": 6.2,
   "days_precip_ge_0_01in": 11.1,
   "days_precip_ge_0_10in": 6.1,
   "days_snow_ge_1_0in": 1.9,
   "days_high_ge_90f": 0.0,
   "days_high_le_32f": 3.4,
   "days_low_le_32f": 21.0,
   "prob_low_le_32f_pct": 100.0
  },
  {
   "month": 4,
   "name": "April",
   "high_f": 58.7,
   "low_f": 39.1,
   "mean_f": 48.9,
   "precip_in": 3.26,
   "snow_in": 1.5,
   "days_precip_ge_0_01in": 12.5,
   "days_precip_ge_0_10in": 7.2,
   "days_snow_ge_1_0in": 0.5,
   "days_high_ge_90f": 0.0,
   "days_high_le_32f": 0.1,
   "days_low_le_32f": 6.2,
   "prob_low_le_32f_pct": 96.7
  },
  {
   "month": 5,
   "name": "May",
   "high_f": 70.3,
   "low_f": 50.2,
   "mean_f": 60.3,
   "precip_in": 3.72,
   "snow_in": 0.0,
   "days_precip_ge_0_01in": 12.9,
   "days_precip_ge_0_10in": 7.7,
   "days_snow_ge_1_0in": 0.0,
   "days_high_ge_90f": 0.5,
   "days_high_le_32f": 0.0,
   "days_low_le_32f": 0.3,
   "prob_low_le_32f_pct": 23.7
  },
  {
   "month": 6,
   "name": "June",
   "high_f": 79.7,
   "low_f": 60.2,
   "mean_f": 69.9,
   "precip_in": 3.26,
   "snow_in": 0.0,
   "days_precip_ge_0_01in": 10.7,
   "days_precip_ge_0_10in": 6.3,
   "days_snow_ge_1_0in": 0.0,
   "days_high_ge_90f": 3.2,
   "days_high_le_32f": 0.0,
   "days_low_le_32f": 0.0,
   "prob_low_le_32f_pct": 0.0
  },
  {
   "month": 7,
   "name": "July",
   "high_f": 83.7,
   "low_f": 64.4,
   "mean_f": 74.1,
   "precip_in": 3.51,
   "snow_in": 0.0,
   "days_precip_ge_0_01in": 10.5,
   "days_precip_ge_0_10in": 6.4,
   "days_snow_ge_1_0in": 0.0,
   "days_high_ge_90f": 5.3,
   "days_high_le_32f": 0.0,
   "days_low_le_32f": 0.0,
   "prob_low_le_32f_pct": 0.0
  },
  {
   "month": 8,
   "name": "August",
   "high_f": 81.4,
   "low_f": 63.2,
   "mean_f": 72.3,
   "precip_in": 3.26,
   "snow_in": 0.0,
   "days_precip_ge_0_01in": 9.7,
   "days_precip_ge_0_10in": 6.1,
   "days_snow_ge_1_0in": 0.0,
   "days_high_ge_90f": 2.7,
   "days_high_le_32f": 0.0,
   "days_low_le_32f": 0.0,
   "prob_low_le_32f_pct": 0.0
  },
  {
   "month": 9,
   "name": "September",
   "high_f": 74.4,
   "low_f": 55.5,
   "mean_f": 64.9,
   "precip_in": 3.22,
   "snow_in": 0.0,
   "days_precip_ge_0_01in": 9.5,
   "days_precip_ge_0_10in": 5.9,
   "days_snow_ge_1_0in": 0.0,
   "days_high_ge_90f": 1.2,
   "days_high_le_32f": 0.0,
   "days_low_le_32f": 0.0,
   "prob_low_le_32f_pct": 0.0
  },
  {
   "month": 10,
   "name": "October",
   "high_f": 62.0,
   "low_f": 44.0,
   "mean_f": 53.0,
   "precip_in": 2.53,
   "snow_in": 0.0,
   "days_precip_ge_0_01in": 10.6,
   "days_precip_ge_0_10in": 5.6,
   "days_snow_ge_1_0in": 0.0,
   "days_high_ge_90f": 0.0,
   "days_high_le_32f": 0.0,
   "days_low_le_32f": 1.9,
   "prob_low_le_32f_pct": 63.9
  },
  {
   "month": 11,
   "name": "November",
   "high_f": 48.6,
   "low_f": 33.9,
   "mean_f": 41.2,
   "precip_in": 2.57,
   "snow_in": 1.9,
   "days_precip_ge_0_01in": 11.0,
   "days_precip_ge_0_10in": 5.6,
   "days_snow_ge_1_0in": 0.6,
   "days_high_ge_90f": 0.0,
   "days_high_le_32f": 1.2,
   "days_low_le_32f": 13.7,
   "prob_low_le_32f_pct": 100.0
  },
  {
   "month": 12,
   "name": "December",
   "high_f": 37.2,
   "low_f": 25.3,
   "mean_f": 31.3,
   "precip_in": 2.25,
   "snow_in": 8.9,
   "days_precip_ge_0_01in": 13.1,
   "days_precip_ge_0_10in": 5.4,
   "days_snow_ge_1_0in": 2.7,
   "days_high_ge_90f": 0.0,
   "days_high_le_32f": 9.5,
   "days_low_le_32f": 24.2,
   "prob_low_le_32f_pct": 100.0
  }
 ],
 "annual": {
  "high_f": 59.1,
  "low_f": 42.0,
  "mean_f": 50.6,
  "precip_in": 34.32,
  "snow_in": 45.0,
  "days_precip_ge_0_01in": 136.0,
  "days_snow_ge_1_0in": 13.6,
  "days_high_ge_90f": 13.0,
  "days_high_le_32f": 41.8,
  "days_low_le_32f": 119.5
 },
 "frost": {
  "semantics": {
   "last_spring": "PRBLST: an N% chance that the last night at or below the threshold comes on or after this date",
   "first_fall": "PRBFST: an N% chance that the first night at or below the threshold has come by this date",
   "season_days": "PRBGSL: length of the season above the threshold, days; P50 is the median"
  },
  "thresholds_f": [
   36,
   32,
   28,
   24,
   20,
   16
  ],
  "probabilities_pct": [
   10,
   20,
   30,
   40,
   50,
   60,
   70,
   80,
   90
  ],
  "table": {
   "36": {
    "status": "computed",
    "freeze_in_most_years": true,
    "last_spring": {
     "10": "05-18",
     "20": "05-12",
     "30": "05-09",
     "40": "05-05",
     "50": "05-02",
     "60": "04-29",
     "70": "04-26",
     "80": "04-22",
     "90": "04-18"
    },
    "first_fall": {
     "10": "10-02",
     "20": "10-06",
     "30": "10-09",
     "40": "10-12",
     "50": "10-15",
     "60": "10-18",
     "70": "10-21",
     "80": "10-25",
     "90": "10-29"
    },
    "season_days": {
     "10": 186.0,
     "20": 178.0,
     "30": 174.0,
     "40": 169.0,
     "50": 165.0,
     "60": 161.0,
     "70": 156.0,
     "80": 151.0,
     "90": 146.0
    }
   },
   "32": {
    "status": "computed",
    "freeze_in_most_years": true,
    "last_spring": {
     "10": "05-08",
     "20": "05-02",
     "30": "04-28",
     "40": "04-23",
     "50": "04-20",
     "60": "04-17",
     "70": "04-15",
     "80": "04-12",
     "90": "04-06"
    },
    "first_fall": {
     "10": "10-14",
     "20": "10-19",
     "30": "10-22",
     "40": "10-25",
     "50": "10-27",
     "60": "10-30",
     "70": "11-01",
     "80": "11-05",
     "90": "11-09"
    },
    "season_days": {
     "10": 207.0,
     "20": 201.0,
     "30": 196.0,
     "40": 192.0,
     "50": 188.0,
     "60": 184.0,
     "70": 180.0,
     "80": 174.0,
     "90": 167.0
    }
   },
   "28": {
    "status": "computed",
    "freeze_in_most_years": true,
    "last_spring": {
     "10": "04-24",
     "20": "04-18",
     "30": "04-15",
     "40": "04-11",
     "50": "04-08",
     "60": "04-05",
     "70": "04-03",
     "80": "04-01",
     "90": "03-27"
    },
    "first_fall": {
     "10": "10-27",
     "20": "11-01",
     "30": "11-03",
     "40": "11-05",
     "50": "11-07",
     "60": "11-10",
     "70": "11-13",
     "80": "11-17",
     "90": "11-22"
    },
    "season_days": {
     "10": 232.0,
     "20": 225.0,
     "30": 221.0,
     "40": 216.0,
     "50": 212.0,
     "60": 208.0,
     "70": 204.0,
     "80": 199.0,
     "90": 193.0
    }
   },
   "24": {
    "status": "computed",
    "freeze_in_most_years": true,
    "last_spring": {
     "10": "04-10",
     "20": "04-05",
     "30": "04-03",
     "40": "03-31",
     "50": "03-29",
     "60": "03-26",
     "70": "03-22",
     "80": "03-19",
     "90": "03-14"
    },
    "first_fall": {
     "10": "11-05",
     "20": "11-09",
     "30": "11-13",
     "40": "11-16",
     "50": "11-19",
     "60": "11-22",
     "70": "11-26",
     "80": "11-29",
     "90": "12-05"
    },
    "season_days": {
     "10": 257.0,
     "20": 249.0,
     "30": 244.0,
     "40": 239.0,
     "50": 235.0,
     "60": 231.0,
     "70": 226.0,
     "80": 222.0,
     "90": 216.0
    }
   },
   "20": {
    "status": "computed",
    "freeze_in_most_years": true,
    "last_spring": {
     "10": "04-01",
     "20": "03-29",
     "30": "03-25",
     "40": "03-22",
     "50": "03-19",
     "60": "03-16",
     "70": "03-13",
     "80": "03-10",
     "90": "03-04"
    },
    "first_fall": {
     "10": "11-13",
     "20": "11-18",
     "30": "11-23",
     "40": "11-26",
     "50": "11-29",
     "60": "12-02",
     "70": "12-06",
     "80": "12-11",
     "90": "12-19"
    },
    "season_days": {
     "10": 277.0,
     "20": 271.0,
     "30": 265.0,
     "40": 260.0,
     "50": 256.0,
     "60": 251.0,
     "70": 246.0,
     "80": 241.0,
     "90": 234.0
    }
   },
   "16": {
    "status": "computed",
    "freeze_in_most_years": true,
    "last_spring": {
     "10": "03-25",
     "20": "03-20",
     "30": "03-17",
     "40": "03-14",
     "50": "03-11",
     "60": "03-07",
     "70": "03-04",
     "80": "02-28",
     "90": "02-22"
    },
    "first_fall": {
     "10": "11-22",
     "20": "11-30",
     "30": "12-02",
     "40": "12-06",
     "50": "12-10",
     "60": "12-14",
     "70": "12-18",
     "80": "12-22",
     "90": "12-26"
    },
    "season_days": {
     "10": 300.0,
     "20": 290.0,
     "30": 284.0,
     "40": 279.0,
     "50": 275.0,
     "60": 271.0,
     "70": 265.0,
     "80": 259.0,
     "90": 250.0
    }
   }
  },
  "notes": []
 },
 "derived": {
  "hottest_month": {
   "month": 7,
   "name": "July",
   "value": 74.1
  },
  "coldest_month": {
   "month": 1,
   "name": "January",
   "value": 25.8
  },
  "hottest_month_by_high": {
   "month": 7,
   "name": "July",
   "value": 83.7
  },
  "wettest_month": {
   "month": 5,
   "name": "May",
   "value": 3.72
  },
  "driest_month": {
   "month": 2,
   "name": "February",
   "value": 2.08
  },
  "snowiest_month": {
   "month": 1,
   "name": "January",
   "value": 14.0
  },
  "winter": "cold",
  "summer": "warm",
  "precipitation": "moderate",
  "snow": "heavy",
  "annual_precip_in": 34.32,
  "annual_snow_in": 45.0,
  "annual_range_f": 48.3,
  "mean_daily_range_f": 17.1,
  "months_high_ge_90f": [],
  "months_low_le_32f": [
   1,
   2,
   3,
   12
  ],
  "last_spring_32f_p50": "04-20",
  "first_fall_32f_p50": "10-27",
  "freeze_free_days_p50": 188.0,
  "freeze_free_span_days_p50": 190
 },
 "rules": {
  "hottest_coldest_month": "by monthly mean temperature (MLY-TAVG-NORMAL); ties go to the earlier month",
  "wettest_driest_month": "by monthly precipitation normal (MLY-PRCP-NORMAL); ties go to the earlier month",
  "winter": {
   "basis": "mean temperature of the coldest month, F",
   "bands": [
    [
     null,
     20,
     "very cold"
    ],
    [
     20,
     32,
     "cold"
    ],
    [
     32,
     45,
     "cool"
    ],
    [
     45,
     60,
     "mild"
    ],
    [
     60,
     null,
     "warm"
    ]
   ]
  },
  "summer": {
   "basis": "mean daily high of the hottest month (by high), F",
   "bands": [
    [
     null,
     70,
     "cool"
    ],
    [
     70,
     80,
     "mild"
    ],
    [
     80,
     90,
     "warm"
    ],
    [
     90,
     100,
     "hot"
    ],
    [
     100,
     null,
     "very hot"
    ]
   ]
  },
  "precipitation": {
   "basis": "annual precipitation normal, inches (sum of months if no annual value)",
   "bands": [
    [
     null,
     10,
     "arid"
    ],
    [
     10,
     20,
     "semi-arid"
    ],
    [
     20,
     40,
     "moderate"
    ],
    [
     40,
     60,
     "wet"
    ],
    [
     60,
     null,
     "very wet"
    ]
   ]
  },
  "snow": {
   "basis": "annual snowfall normal, inches; 'no data' when NOAA publishes no snowfall normal",
   "bands": [
    [
     null,
     1,
     "rare or none"
    ],
    [
     1,
     12,
     "light"
    ],
    [
     12,
     36,
     "moderate"
    ],
    [
     36,
     72,
     "heavy"
    ],
    [
     72,
     null,
     "very heavy"
    ]
   ]
  },
  "bands": "lower bound inclusive, upper bound exclusive",
  "frost_free": "true when the 32F last-spring and first-fall P50 dates are -9999 with flag Y (insufficient values) and the 32F growing season P50 is 365 days or the annual number of nights at or below 32F rounds to 0.0",
  "freeze_free_days_p50": "NOAA ANN-TMIN-PRBGSL-T32FP50 (median length of the 32F freeze-free season), as published",
  "freeze_rare": "true when 32F dates are published but the 32F growing season P50 is 365 days: no 32F night in at least half of years; the P50 spring and fall dates then cross and freeze_free_span_days_p50 is null",
  "freeze_free_span_days_p50": "days from the 32F P50 last-spring date to the 32F P50 first-fall date (next year if the fall date is earlier in the calendar); differs from the NOAA median season length because a median of lengths is not the span between median dates"
 },
 "flags": {
  "frost_free": false,
  "freeze_rare": false,
  "frost_data_missing": false,
  "year_round_frost_risk": false,
  "snow_normal_absent": false,
  "incomplete_months": []
 },
 "quality": {
  "high_f": {
   "column": "MLY-TMAX-NORMAL",
   "absent": false,
   "comp_flags": [
    "S"
   ],
   "meas_flags": [],
   "years_min": 25,
   "missing_months": 0
  },
  "low_f": {
   "column": "MLY-TMIN-NORMAL",
   "absent": false,
   "comp_flags": [
    "S"
   ],
   "meas_flags": [],
   "years_min": 28,
   "missing_months": 0
  },
  "mean_f": {
   "column": "MLY-TAVG-NORMAL",
   "absent": false,
   "comp_flags": [
    "S"
   ],
   "meas_flags": [],
   "years_min": 25,
   "missing_months": 0
  },
  "precip_in": {
   "column": "MLY-PRCP-NORMAL",
   "absent": false,
   "comp_flags": [
    "S"
   ],
   "meas_flags": [],
   "years_min": 30,
   "missing_months": 0
  },
  "snow_in": {
   "column": "MLY-SNOW-NORMAL",
   "absent": false,
   "comp_flags": [
    "S"
   ],
   "meas_flags": [
    "X"
   ],
   "years_min": 29,
   "missing_months": 0
  },
  "days_precip_ge_0_01in": {
   "column": "MLY-PRCP-AVGNDS-GE001HI",
   "absent": false,
   "comp_flags": [
    "S"
   ],
   "meas_flags": [],
   "years_min": 30,
   "missing_months": 0
  },
  "days_precip_ge_0_10in": {
   "column": "MLY-PRCP-AVGNDS-GE010HI",
   "absent": false,
   "comp_flags": [
    "S"
   ],
   "meas_flags": [],
   "years_min": 30,
   "missing_months": 0
  },
  "days_snow_ge_1_0in": {
   "column": "MLY-SNOW-AVGNDS-GE010TI",
   "absent": false,
   "comp_flags": [
    "S"
   ],
   "meas_flags": [],
   "years_min": 29,
   "missing_months": 0
  },
  "days_high_ge_90f": {
   "column": "MLY-TMAX-AVGNDS-GRTH090",
   "absent": false,
   "comp_flags": [
    "S"
   ],
   "meas_flags": [
    "X"
   ],
   "years_min": 25,
   "missing_months": 0
  },
  "days_high_le_32f": {
   "column": "MLY-TMAX-AVGNDS-LSTH032",
   "absent": false,
   "comp_flags": [
    "S"
   ],
   "meas_flags": [],
   "years_min": 25,
   "missing_months": 0
  },
  "days_low_le_32f": {
   "column": "MLY-TMIN-AVGNDS-LSTH032",
   "absent": false,
   "comp_flags": [
    "S"
   ],
   "meas_flags": [],
   "years_min": 28,
   "missing_months": 0
  },
  "prob_low_le_32f_pct": {
   "column": "MLY-TMIN-PRBOCC-LSTH032",
   "absent": false,
   "comp_flags": [
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   ],
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   "years_min": 28,
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 },
 "citation": {
  "monthly": "Palecki, Michael; Durre, Imke; Applequist, Scott; Arguez, Anthony; Lawrimore, Jay (2021). U.S. Climate Normals 2020: U.S. Monthly Climate Normals (1991-2020). Station USW00094847 (DETROIT METRO AP, MI US). NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/wck8-er13. Accessed 2026-10-09.",
  "annual": "Palecki, Michael; Durre, Imke; Applequist, Scott; Arguez, Anthony; Lawrimore, Jay (2021). U.S. Climate Normals 2020: U.S. Annual/Seasonal Climate Normals (1991-2020). Station USW00094847 (DETROIT METRO AP, MI US). NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/4ek7-fk11. Accessed 2026-10-09.",
  "metadata_records": [
   "https://www.ncei.noaa.gov/access/metadata/landing-page/bin/iso?id=gov.noaa.ncdc:C01620",
   "https://www.ncei.noaa.gov/access/metadata/landing-page/bin/iso?id=gov.noaa.ncdc:C01619"
  ]
 },
 "retrieved": {
  "monthly": "2026-10-09",
  "annual": "2026-10-09"
 }
}