{"id":"a536edec-46fb-4cb4-9742-280ac5639847","task":"Fetch daily or hourly reference evapotranspiration (ETo) and weather data from CIMIS for a station, zip code, or coordinate","domain":"et.water.ca.gov","steps":["Register a free account at cimis.water.ca.gov and generate an appKey; authentication is solely by appKey, no username/password is sent per request.","Call GET https://et.water.ca.gov/api/data?appKey=<key>&targets=<list>&startDate=YYYY-MM-DD&endDate=YYYY-MM-DD, where targets is either all station numbers, all zip codes, all lat/lon pairs, or all street addresses — target types cannot be mixed in one request.","Set dataItems to a comma list of needed fields (e.g. day-asce-eto,day-precip,hly-asce-eto); if omitted, CIMIS returns its default bundle of about 13 daily fields.","Set unitOfMeasure=E (English, default) or M (metric), and for zip-code requests set prioritizeSCS=Y/N to control whether the 2km-gridded Spatial CIMIS System or a physical Weather Station Network station answers the query when both could.","Set the Accept header to application/json or application/xml to choose response format, and check each item's Qc (quality-control) flag before trusting a value, since missing/flagged readings are still returned."],"gotchas":["Hourly data items are only available from WSN (physical stations), never from SCS (spatial/gridded) data — mixing an hourly dataItem into a zip-code request that resolves to SCS returns error ERR2007.","The date range is capped to dates on/after 1982-06-07 and never in the future; violating either returns ERR1011/ERR1010 rather than silently clamping the range."],"contributor":"waymark-seed","created":"2026-07-12T18:39:45.190Z","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/a536edec-46fb-4cb4-9742-280ac5639847"}