NOAA NCEI

The National Centers for Environmental Information (NCEI) are the data archive of the US National Oceanic and Atmospheric Administration (NOAA), within its satellite and data service, NESDIS.⁹ It keeps oceanic, atmospheric and geophysical data, and its products run from weather station records, severe weather and climate monitoring to ocean temperature, marine geology, paleoclimate and space weather.^1,11 Data and sites still at older addresses, ncdc.noaa.gov, ngdc.noaa.gov and nodc.noaa.gov, are moving to ncei.noaa.gov.¹⁰ The archive and its backup hold more than 60 petabytes, and it adds over 229 terabytes a month from more than 130 observing platforms.^1,2

Two of its datasets are the usual starting point for a place. The Global Historical Climatology Network daily (GHCNd) gathers daily records from more than 100,000 land stations in 180 countries and territories: highest and lowest temperature, rainfall, snowfall and snow depth, though about half the stations report only precipitation.⁵ Records run from under a year to more than 175 years, are updated daily, and pass a common set of quality checks.⁵ The US Climate Normals give typical conditions, the 30-year averages and statistics of temperature, precipitation and other variables, for almost 15,000 US stations; the current set covers 1991 to 2020, and monthly gridded normals cover the contiguous US.⁶

Access is free.⁴ Climate Data Online lets a user find past weather by station, ZIP code, city, county, state or country, and certified copies for legal use can be ordered for a fee.⁴ NCEI Data Access offers downloads and subsets in CSV, PDF, shapefile and other formats, and NOAA OneStop searches more than 104,000 collections across NOAA.³ There are two APIs: the NCEI Access Data Service, which returns CSV, JSON, PDF or NetCDF depending on the dataset, and the Climate Data Online web services, which need a free token and allow five requests a second and 10,000 a day.^7,8 NOAA is moving NCEI's data and applications to Amazon's cloud through spring 2027; addresses on ncei.noaa.gov stay the same, bulk folders move to S3, and many datasets will also come in cloud formats such as Zarr and Parquet.^9,10 The FAQ says no datasets will be retired by the move, though several were retired in the preceding 18 months.¹⁰

For someone modelling a place, NCEI holds the measured weather record: daily temperature and rainfall from the nearest stations to calibrate or check a model, and the Climate Normals as the baseline that a heat, flood or crop study compares its future against.^5,6 Station records are points; for a continuous grid of past weather see ERA5, and for the wider question see Weather and climate.