# Weather History

> Free weather history explorer: pick a city or one of 7,855 NOAA GHCN-Daily weather stations and see any year's daily
> temperatures, precipitation, snow and wind against that station's 1991-2020 normals and records.

URL: https://weather-history.skillsafe.ai/

## What it does

- Station picker: search by city, airport, station name, country, U.S. state or GHCN-Daily ID; 28 major-city shortcuts;
  "near me" (nearest stations by distance); six bundled examples (Seattle, New York, Phoenix, Berlin, Toronto, Sydney) that
  load instantly without an account. Period: since 1991, or the station's full record (back to the 1800s at some stations).
- For the chosen year: mean temperature against normal, hottest day, coldest night, precipitation as a percent of normal to
  date, wettest day, days with 1 mm or more, hot days (30 C / 86 F or more), frost nights, snowfall, windiest day, and the
  count of daily record highs and lows set.
- Charts: daily high-low bars over the normal band and the record band, with record-setting days marked; cumulative
  precipitation against normal; monthly precipitation against normal; 7-day mean temperature and 14-day mean wind for up to
  six years side by side; kinds of day by month (dry, light, moderate, heavy rain, snow); on-this-day normals, records and
  rain chance; warming stripes and annual mean temperature with an ordinary least-squares trend per decade.
- Tables: top-10 hottest days, coldest nights, wettest, snowiest and windiest days; the daily data for any month.
- Export: daily CSV (whole record or one year), each chart as SVG, a shareable link (#s=<station>&y=<year>).
- Your own data: a CSV with a date column and max/min temperature and/or precipitation (GHCN-Daily, Open-Meteo, Meteostat
  and generic exports; Celsius or Fahrenheit, mm or inches detected from headers) is analysed in the browser and never uploaded.
- Celsius/Fahrenheit switch, light and dark themes, works on phones.

## Methods

- Normals: per-calendar-day means over 1991-2020 (needs 20+ years at least 80% complete), smoothed with a circular 31-day
  window; otherwise every complete year, labelled. Monthly precipitation normals average months at least 90% complete.
- Records: strictly beats every earlier year for that calendar day within the loaded years; needs 10 earlier years; ties are not records.
- Station data are not homogenised.

## Data source

NOAA National Centers for Environmental Information, Global Historical Climatology Network - Daily (GHCN-Daily), Version 3.
Menne, M.J., et al. (2012), doi:10.7289/V5D21VHZ. A U.S. government dataset. Live station data is fetched through the app's
server function (GET /api/daily), which needs a free SkillSafe sign-in and costs no credits. See /api.html.

## Price

Free. No model and no credits.