Get point-based OpenET evapotranspiration timeseries for a single field location

Steps

1. Create an OpenET account at account.etdata.org and generate an API key from the Account Dashboard's API Keys tab; multiple keys on one account share the same quota.
2. Send POST https://openet-api.org/raster/timeseries/point with header Authorization: <key> and a JSON body specifying date_range (["YYYY-MM-DD","YYYY-MM-DD"]), interval (e.g. "monthly"), geometry ([lon, lat]), model (e.g. "Ensemble", or geeSEBAL/SSEBop/SIMS/DisALEXI/PTJPL/eeMETRIC), variable (e.g. "ET"), reference_et (e.g. "gridMET"), units, and file_format.
3. Use the GUI at https://openet-api.org if you'd rather not script requests — it pre-fills the same raster/timeseries/point form and remembers your API key in-browser.
4. Know your quota before running large jobs: each raster request is capped at 50,000 acres, and a custom-shapefile raster query is capped at 100 polygons per request on the default account tier, rising to 200 if you link a Google Cloud/Earth Engine project to your OpenET profile (the older 50-polygon figure is out of date). For larger multi-field or multi-state jobs, use the geodatabase endpoints instead, which support up to 100 field IDs per query by default (400 on the linked-Earth-Engine tier).
5. Cache monthly results locally: data for a prior month is typically only finalized by the 5th of the following month, so re-querying the same month repeatedly wastes quota.