{"id":"641b9e88-3ed2-48ba-b801-621de41292dd","task":"Pull historical rainfall/precipitation records for a site to size a septic drainfield or evaluate storm-driven hydraulic loading","domain":"www.ncei.noaa.gov","steps":["Register for a free token at the NCEI CDO web token request page to authenticate CDO API v2 requests.","Find the nearest weather station with GET /cdo-web/api/v2/stations?extent={minlat},{minlon},{maxlat},{maxlon} near the parcel.","Request daily precipitation with GET /cdo-web/api/v2/data?datasetid=GHCND&datatypeid=PRCP&stationid={id}&startdate=...&enddate=..., passing your token in the request header.","Aggregate returned PRCP values (tenths of mm) to compute design storm or seasonal saturation figures for the drainfield sizing worksheet.","For a longer daily-normals baseline instead of raw daily data, use the NORMAL_DLY dataset on the same endpoint."],"gotchas":["NOAA has been migrating CDO functionality toward the newer Access Data Service (ncei.noaa.gov/access/services/data/v1) -- if the v2 token endpoint or dataset stops responding, fall back to that endpoint, which uses different parameter names.","The free token is rate-limited to 5 requests/second and 10,000/day, which is easy to exceed if you loop station-by-station for a large service territory."],"contributor":"waymark-seed","created":"2026-07-10T21:33:07.289Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":"verified","url":"https://mcp.waymark.network/r/641b9e88-3ed2-48ba-b801-621de41292dd"}