• Window: 2020-01-01 to the most recent completed day. Report times are UTC. The climate date is on each station's fixed standard-time offset (no daylight saving).
• Grain: one row per report, in one table per city. Routine reports are hourly. Special reports arrive when conditions change, so a day holds roughly 24 to 60 rows.
• Cadence: refreshed hourly at five minutes past the hour (UTC). Official NWS daily highs and lows update as the daily climate reports are published.
• Cities 1 to 10: Atlanta, Austin, Boston, Chicago, Dallas-Fort Worth, Washington D.C., Denver, Houston, Las Vegas and Los Angeles.
• Cities 11 to 20: Miami, Minneapolis-Saint Paul, New Orleans, New York City, Oklahoma City, Philadelphia, Phoenix, San Antonio, Seattle and San Francisco.

• station, event_time_utc, observation_type: ICAO station, report time in UTC, METAR or SPECI.
• local_standard_date: the climate date the report belongs to, fixed standard time.
• temp_f, dewpoint_f, relative_humidity_pct: temperature and dew point in degrees Fahrenheit, humidity in percent.
• wind_direction_degrees, wind_speed_kt, wind_gust_kt, peak_wind_gust_kt, peak_wind_direction_degrees, peak_wind_time: wind, knots and degrees.
• altimeter_inhg, sea_level_pressure_hpa: pressure.
• sky_cover_1 to sky_cover_4, sky_base_1_ft to sky_base_4_ft: cloud layers and their bases in feet.
• visibility_miles, weather_codes, precipitation_in_1h, snow_depth_inches: visibility, present weather, hourly precipitation in inches, snow depth.
• raw_metar: the original report text.
• cli_high_f, cli_low_f: the official NWS daily maximum and minimum for the report's climate date, in degrees Fahrenheit.
• cli_product, cli_report_type: the source product and whether the product was preliminary, final or corrected.

Report fields are null when absent from a report. Official values are null on the few dates with no archived NWS report. Official values are never estimated from observations.

• Predict the day's official high or low from the reports seen so far.
• Settle or evaluate daily temperature forecasts and markets.
• Train on hourly conditions with the official outcome as the label.
• Build daily aggregates by grouping on local_standard_date.

National Weather Service (NWS) CLI reports and ASOS/METAR observations are US Government works (17 U.S.C. 105), archived and redistributed by the Iowa Environmental Mesonet, which requests attribution. Each city maps to one measurement station, not the metropolitan area. This compilation is released under CC0 1.0.