SourcesThe data family
climatedata.dev
Free, versioned monthly temperature and precipitation for every US county since 1895, from NOAA's nClimDiv, plus global temperature and greenhouse-gas records, with citable URLs.
What it is
climatedata.dev is a free public-data site for climate records. It republishes monthly temperature and precipitation for US counties, states and the nation from NOAA’s National Centers for Environmental Information (NCEI), along with global records from NOAA, NASA and the UK Met Office. It serves them as plain files and a simple API, with no key or signup. Like this site, it’s run by Eric Ness.
The US figures come from nClimDiv, NOAA’s Monthly U.S. Climate Divisional Database. Every dataset names its publisher, its license and the exact credit line to use.
What it measures
The site has six datasets, all updated monthly.
- County climate report card. Monthly average, maximum and minimum temperature (°F) and precipitation (inches) for every US county, from nClimDiv: the contiguous US from 1895, Alaska from 1925 and Hawaii from 1991. Each month comes with NCEI’s 1991–2020 normal, the anomaly from that normal, and its rank among all years for that calendar month.
- State and national climate. The same four measures for each state and the contiguous United States, also from nClimDiv.
- Global surface temperature. Monthly global and hemispheric anomalies from NASA’s GISTEMP v4 (from 1880, against 1951–1980) and the Met Office’s HadCRUT5 (from 1850, against 1961–1990, with a 95 percent confidence range).
- Monthly atmospheric CO2. Carbon dioxide at Mauna Loa Observatory from 1958 and the global marine-surface average from 1979, from NOAA’s Global Monitoring Laboratory, with the seasonal cycle removed as a trend.
- Global methane and nitrous oxide. Monthly global means from NOAA’s air sampling network: methane from July 1983, nitrous oxide from January 2001.
- World capitals climate. Monthly air temperature at each country’s capital from NASA’s POWER project (MERRA-2 reanalysis, from 1981), with normals, anomalies and ranks that climatedata.dev computes itself.
What the site adds: one schema and one place-ID scheme shared with its sister sites (us-county- plus the five-digit FIPS code, us-ca for states), the normal, anomaly and rank next to each value, files in JSON, CSV and Parquet, a version for every update, and checks before each one is published. If a check fails, the last good version stays live. It also builds three yearly indicators that visualizedata.org charts.
What it misses
County values are estimates, not readings. NOAA builds nClimDiv county values by interpolating station data onto a grid about 5 km across, then averaging the grid points in each county. A county’s number is not a reading from a station in that county. The stations come from the Global Historical Climatology Network, and NOAA adjusts temperatures for changes in observation time, station location and instruments. The methods are published, but the series is a built record, not raw observations.
Recent numbers change. NOAA’s readme says values from the latest two calendar years are updated every month, and the whole record changes when the dataset gets a new version. A figure you pulled in the spring may differ by autumn.
Short records in two states. County data starts in 1925 for Alaska and 1991 for Hawaii, so a rank there compares against far fewer years than in the contiguous US.
The global series don’t share a baseline. GISTEMP and HadCRUT5 measure anomalies against different 30-year periods, so their numbers aren’t directly comparable. The capital-city series is one point per country, not the whole country, and comes from a reanalysis model rather than a station.
It’s a copy. For anything high-stakes, check the figure against NOAA’s Climate at a Glance or the agency’s own files.
How to access it
1Browse the datasets
Start at climatedata.dev/datasets/. Each dataset page shows its coverage, schema, license, credit line and every endpoint, with a chart.
2Download the whole dataset
Each dataset is one CSV or Parquet file, at /v1/{dataset}/download/{dataset}.csv (or .parquet). Parquet keeps column types and is much smaller.
3Call the API
The base URL is https://api.climatedata.dev/v1. The catalog at /v1/catalog lists each dataset with its current version and coverage. Each series for each place is its own small file, at /v1/{dataset}/{series}/{location}.json (or .csv). The county series IDs are tavg, tmax, tmin and pcpn.
For example, https://api.climatedata.dev/v1/county-climate/tavg/us-county-06037.csv returns monthly average temperature for Los Angeles County. Tested on 2026-11-14, it returned months from 1895-01 to 2026-10, each with its value, normal, anomaly and rank. October 2026 came back at 67.7 °F against a normal of 64.8 °F.
4Read the docs
The docs cover the URL scheme, place IDs, formats, versions, caching and errors. The API reference lists the exact URLs. Without a key you can make 120 requests a minute from one IP address, so download the bulk file for large pulls. The status page shows whether each dataset is current.
How to cite it
Cite the version you used, and credit the source with the exact text given on each dataset page and the sources page. For county data, that credit is the nClimDiv dataset citation: Vose and others (2014), NOAA Monthly U.S. Climate Divisional Database (NClimDiv), doi:10.7289/V5M32STR.
Every update gets a version ID: the publish date plus the start of a hash, such as 2026-11-10.afa0f9af0a. Put it after the dataset ID with @ to pin it, and a pinned URL always returns the same data. The site says to cite the monthly snapshots, the first version of each month, because those are kept permanently. Other versions may be removed after 30 days. /v1/{dataset}/versions lists them.
A worked example, for Los Angeles County in the November 2026 snapshot:
Vose, R. S., et al. (2014). NOAA Monthly U.S. Climate Divisional Database (NClimDiv), county average temperature, Los Angeles County, CA. NOAA National Climatic Data Center. doi:10.7289/V5M32STR. Retrieved via climatedata.dev, county-climate version 2026-11-10.afa0f9af0a, https://api.climatedata.dev/v1/county-climate@2026-11-10.afa0f9af0a/tavg/us-county-06037.csv, accessed 14 November 2026.
Sources & further reading
End of page · Back to top