Retrieve heating degree days from NOAA's Climate Data Online (CDO) API
domain: www.ncdc.noaa.gov · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Request an access token from the CDO token request page (free registration).
Send requests to the CDO web services v2 base URL with the token in a token header.
Query /datasets to confirm which dataset carries the heating-degree-day (HTDD) data type for your area of interest.
Query /data with datasetid, a locationid or stationid, and startdate/enddate parameters to pull the actual values.
Optionally filter with datatypeid to restrict the response to the HTDD data type specifically.
Known gotchas
The API enforces a hard limit of five requests per second and 10,000 requests per day per token.
HTDD values in the monthly summaries dataset are monthly totals on a 65 degF base — confirm the unit (whole degF vs. tenths of degC) matches your account's output preference before using the numbers.
startdate/enddate ranges are capped (roughly a 10-year range for annual/monthly data, 1-year for finer-grained data) — long historical pulls must be paginated across multiple date-range requests.
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