Data Downloads: CSV and JSON Files With a Field Dictionary

• 8,896 tables are available as CSV and as JSON, one pair for each data page.
• Temperatures are in degrees Celsius with one decimal and precipitation in millimetres with one decimal in every file; Fahrenheit and inches are shown on pages only.
• Dates are ISO 8601 (YYYY-MM-DD). Every JSON file carries a data as of date, a last revised date, the source and the licence.
• 0 cities have a compact daily history file in format wem-history-1: one row per day, the date as YYYYMMDD and five values in tenths.

• Every data page has a Download the Data section with a CSV and a JSON link for the table it shows.
• The files live at /data/files/{family}/{id}.csv and .json: for example /data/files/records.csv.
• CSV files have one header row, comma separators and quoted text where needed. JSON files hold the same rows as objects, with the field dictionary, the data as of date, the last revised date, the source and the licence.
• Data comes from NOAA GHCN-Daily (US Government open data (NOAA NCEI)) and is free to reuse with attribution. Records are computed by this site and are not official.

The threshold explorer reads one compact full-history file per city (and per eligible station in the production export). A file holds the date and five values for every day of the record.

{
  "format": "wem-history-1",
  "id": "phoenix",
  "name": "Phoenix",
  "asOf": "",
  "revised": "",
  "fields": ["tmax","tmin","prcp","snow","snwd"],
  "scale": 10,
  "rows": [
    
  ]
}

• Each row is [YYYYMMDD, tmax, tmin, prcp, snow, snwd]. The date is a whole number such as 19480101.
• Values are whole numbers in tenths: tenths of a degree Celsius for temperature and tenths of a millimetre for precipitation, snowfall and snow depth. Divide by scale (10) for degrees or millimetres. A missing value is null.
• Rows are sorted by date and cover every calendar day with any observation. Files are served gzip compressed.
• A threshold of 40 C is 400; a threshold of 100 F is converted once to tenths of a degree Celsius, rounding half up, which is 378.
• The same engine runs in the browser and in the build; tests compare it with a slow reference implementation and with the per year counts on the city pages.