{ "slug": "seattle-wa", "place": { "name": "Seattle", "state": "WA", "census_name": "Seattle city", "census_geoid": "5363000", "lat": 47.61933, "lon": -122.35154, "station_distance_km": 19.7 }, "station": { "id": "USW00024233", "name": "SEATTLE TACOMA INTL AP, WA US", "lat": 47.4444, "lon": -122.3139, "elevation_m": 112.8, "elevation_ft": 370, "source_urls": { "monthly": "https://www.ncei.noaa.gov/data/normals-monthly/1991-2020/access/USW00024233.csv", "annual": "https://www.ncei.noaa.gov/data/normals-annualseasonal/1991-2020/access/USW00024233.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": 48.0, "low_f": 37.7, "mean_f": 42.8, "precip_in": 5.78, "snow_in": 1.8, "days_precip_ge_0_01in": 18.7, "days_precip_ge_0_10in": 12.7, "days_snow_ge_1_0in": 0.4, "days_high_ge_90f": 0.0, "days_high_le_32f": 0.4, "days_low_le_32f": 7.0, "prob_low_le_32f_pct": 89.6 }, { "month": 2, "name": "February", "high_f": 50.3, "low_f": 37.7, "mean_f": 44.0, "precip_in": 3.76, "snow_in": 2.2, "days_precip_ge_0_01in": 15.9, "days_precip_ge_0_10in": 9.3, "days_snow_ge_1_0in": 0.7, "days_high_ge_90f": 0.0, "days_high_le_32f": 0.1, "days_low_le_32f": 5.8, "prob_low_le_32f_pct": 85.4 }, { "month": 3, "name": "March", "high_f": 54.2, "low_f": 39.9, "mean_f": 47.1, "precip_in": 4.17, "snow_in": 0.4, "days_precip_ge_0_01in": 17.1, "days_precip_ge_0_10in": 10.9, "days_snow_ge_1_0in": 0.1, "days_high_ge_90f": 0.0, "days_high_le_32f": 0.0, "days_low_le_32f": 1.9, "prob_low_le_32f_pct": 53.4 }, { "month": 4, "name": "April", "high_f": 59.3, "low_f": 43.3, "mean_f": 51.3, "precip_in": 3.18, "snow_in": 0.0, "days_precip_ge_0_01in": 15.0, "days_precip_ge_0_10in": 8.7, "days_snow_ge_1_0in": 0.0, "days_high_ge_90f": 0.0, "days_high_le_32f": 0.0, "days_low_le_32f": 0.1, "prob_low_le_32f_pct": 1.5 }, { "month": 5, "name": "May", "high_f": 66.3, "low_f": 48.7, "mean_f": 57.5, "precip_in": 1.88, "snow_in": 0.0, "days_precip_ge_0_01in": 11.3, "days_precip_ge_0_10in": 5.8, "days_snow_ge_1_0in": 0.0, "days_high_ge_90f": 0.0, "days_high_le_32f": 0.0, "days_low_le_32f": 0.0, "prob_low_le_32f_pct": 0.0 }, { "month": 6, "name": "June", "high_f": 71.1, "low_f": 53.0, "mean_f": 62.0, "precip_in": 1.45, "snow_in": 0.0, "days_precip_ge_0_01in": 9.2, "days_precip_ge_0_10in": 4.3, "days_snow_ge_1_0in": 0.0, "days_high_ge_90f": 0.6, "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": 77.4, "low_f": 56.8, "mean_f": 67.1, "precip_in": 0.6, "snow_in": 0.0, "days_precip_ge_0_01in": 4.7, "days_precip_ge_0_10in": 1.8, "days_snow_ge_1_0in": 0.0, "days_high_ge_90f": 1.8, "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": 77.6, "low_f": 57.2, "mean_f": 67.4, "precip_in": 0.97, "snow_in": 0.0, "days_precip_ge_0_01in": 4.9, "days_precip_ge_0_10in": 2.3, "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": 9, "name": "September", "high_f": 71.6, "low_f": 53.6, "mean_f": 62.6, "precip_in": 1.61, "snow_in": 0.0, "days_precip_ge_0_01in": 8.3, "days_precip_ge_0_10in": 4.2, "days_snow_ge_1_0in": 0.0, "days_high_ge_90f": 0.2, "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": 60.5, "low_f": 47.0, "mean_f": 53.8, "precip_in": 3.91, "snow_in": 0.0, "days_precip_ge_0_01in": 14.3, "days_precip_ge_0_10in": 8.4, "days_snow_ge_1_0in": 0.0, "days_high_ge_90f": 0.0, "days_high_le_32f": 0.0, "days_low_le_32f": 0.2, "prob_low_le_32f_pct": 3.9 }, { "month": 11, "name": "November", "high_f": 52.1, "low_f": 40.9, "mean_f": 46.5, "precip_in": 6.31, "snow_in": 0.2, "days_precip_ge_0_01in": 18.4, "days_precip_ge_0_10in": 12.9, "days_snow_ge_1_0in": 0.1, "days_high_ge_90f": 0.0, "days_high_le_32f": 0.1, "days_low_le_32f": 3.0, "prob_low_le_32f_pct": 64.2 }, { "month": 12, "name": "December", "high_f": 47.0, "low_f": 37.1, "mean_f": 42.0, "precip_in": 5.72, "snow_in": 1.7, "days_precip_ge_0_01in": 18.4, "days_precip_ge_0_10in": 12.1, "days_snow_ge_1_0in": 0.6, "days_high_ge_90f": 0.0, "days_high_le_32f": 0.5, "days_low_le_32f": 7.2, "prob_low_le_32f_pct": 93.8 } ], "annual": { "high_f": 61.3, "low_f": 46.1, "mean_f": 53.7, "precip_in": 39.34, "snow_in": 6.3, "days_precip_ge_0_01in": 156.2, "days_snow_ge_1_0in": 1.9, "days_high_ge_90f": 3.8, "days_high_le_32f": 1.2, "days_low_le_32f": 25.2 }, "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": "04-21", "20": "04-12", "30": "04-06", "40": "04-02", "50": "03-31", "60": "03-28", "70": "03-24", "80": "03-18", "90": "03-13" }, "first_fall": { "10": "10-24", "20": "10-29", "30": "11-01", "40": "11-04", "50": "11-07", "60": "11-11", "70": "11-14", "80": "11-17", "90": "11-23" }, "season_days": { "10": 244.0, "20": 235.0, "30": 229.0, "40": 224.0, "50": 219.0, "60": 215.0, "70": 210.0, "80": 204.0, "90": 195.0 } }, "32": { "status": "computed", "freeze_in_most_years": true, "last_spring": { "10": "03-23", "20": "03-16", "30": "03-12", "40": "03-07", "50": "03-02", "60": "02-27", "70": "02-22", "80": "02-16", "90": "02-05" }, "first_fall": { "10": "11-06", "20": "11-11", "30": "11-14", "40": "11-18", "50": "11-23", "60": "11-28", "70": "12-02", "80": "12-07", "90": "12-15" }, "season_days": { "10": 298.0, "20": 286.0, "30": 279.0, "40": 272.0, "50": 266.0, "60": 260.0, "70": 254.0, "80": 246.0, "90": 239.0 } }, "28": { "status": "computed", "freeze_in_most_years": true, "last_spring": { "10": "02-28", "20": "02-23", "30": "02-18", "40": "02-13", "50": "02-04", "60": "01-27", "70": "01-17", "80": "01-05", "90": "12-20" }, "first_fall": { "10": "11-17", "20": "11-24", "30": "11-30", "40": "12-05", "50": "12-10", "60": "12-15", "70": "12-23", "80": "01-01", "90": "01-16" }, "season_days": { "10": 352.0, "20": 339.0, "30": 331.0, "40": 322.0, "50": 315.0, "60": 307.0, "70": 300.0, "80": 289.0, "90": 277.0 } }, "24": { "status": "computed", "freeze_in_most_years": true, "last_spring": { "10": "02-17", "20": "02-04", "30": "01-25", "40": "01-15", "50": "01-04", "60": "12-30", "70": "12-19", "80": "12-13", "90": "12-05" }, "first_fall": { "10": "11-26", "20": "12-03", "30": "12-08", "40": "12-12", "50": "12-17", "60": "12-24", "70": "01-01", "80": "01-10", "90": "02-01" }, "season_days": { "10": 365.0, "20": 365.0, "30": 365.0, "40": 365.0, "50": 355.0, "60": 344.0, "70": 336.0, "80": 329.0, "90": 316.0 } }, "20": { "status": "computed", "freeze_in_most_years": false, "last_spring": { "10": "01-28", "20": "01-14", "30": "01-01", "40": "12-27", "50": "12-18", "60": "12-14", "70": "12-11", "80": "12-06", "90": "11-30" }, "first_fall": { "10": "11-26", "20": "12-04", "30": "12-08", "40": "12-12", "50": "12-16", "60": "12-21", "70": "12-29", "80": "01-02", "90": "01-24" }, "season_days": { "10": 365.0, "20": 365.0, "30": 365.0, "40": 365.0, "50": 365.0, "60": 365.0, "70": 365.0, "80": 363.0, "90": 339.0 } }, "16": { "status": "no_freeze_typical_year", "freeze_in_most_years": false, "last_spring": { "10": null, "20": null, "30": null, "40": null, "50": null, "60": null, "70": null, "80": null, "90": null }, "first_fall": { "10": null, "20": null, "30": null, "40": null, "50": null, "60": null, "70": null, "80": null, "90": null }, "season_days": { "10": 365.0, "20": 365.0, "30": 365.0, "40": 365.0, "50": 365.0, "60": 365.0, "70": 365.0, "80": 365.0, "90": 365.0 } } }, "notes": [ "T16: null cells carry NCEI flags ['Y']" ] }, "derived": { "hottest_month": { "month": 8, "name": "August", "value": 67.4 }, "coldest_month": { "month": 12, "name": "December", "value": 42.0 }, "hottest_month_by_high": { "month": 8, "name": "August", "value": 77.6 }, "wettest_month": { "month": 11, "name": "November", "value": 6.31 }, "driest_month": { "month": 7, "name": "July", "value": 0.6 }, "snowiest_month": { "month": 2, "name": "February", "value": 2.2 }, "winter": "cool", "summer": "mild", "precipitation": "moderate", "snow": "light", "annual_precip_in": 39.34, "annual_snow_in": 6.3, "annual_range_f": 25.4, "mean_daily_range_f": 15.2, "months_high_ge_90f": [], "months_low_le_32f": [], "last_spring_32f_p50": "03-02", "first_fall_32f_p50": "11-23", "freeze_free_days_p50": 266.0, "freeze_free_span_days_p50": 266 }, "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": 30, "missing_months": 0 }, "low_f": { "column": "MLY-TMIN-NORMAL", "absent": false, "comp_flags": [ "S" ], "meas_flags": [], "years_min": 25, "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": 29, "missing_months": 0 }, "snow_in": { "column": "MLY-SNOW-NORMAL", "absent": false, "comp_flags": [ "P" ], "meas_flags": [], "years_min": 17, "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": [ "P" ], "meas_flags": [], "years_min": 17, "missing_months": 0 }, "days_high_ge_90f": { "column": "MLY-TMAX-AVGNDS-GRTH090", "absent": false, "comp_flags": [ "S" ], "meas_flags": [ "X" ], "years_min": 30, "missing_months": 0 }, "days_high_le_32f": { "column": "MLY-TMAX-AVGNDS-LSTH032", "absent": false, "comp_flags": [ "S" ], "meas_flags": [], "years_min": 30, "missing_months": 0 }, "days_low_le_32f": { "column": "MLY-TMIN-AVGNDS-LSTH032", "absent": false, "comp_flags": [ "S" ], "meas_flags": [], "years_min": 25, "missing_months": 0 }, "prob_low_le_32f_pct": { "column": "MLY-TMIN-PRBOCC-LSTH032", "absent": false, "comp_flags": [ "S" ], "meas_flags": [], "years_min": 25, "missing_months": 0 } }, "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 USW00024233 (SEATTLE TACOMA INTL AP, WA 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 USW00024233 (SEATTLE TACOMA INTL AP, WA 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" } }