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FreeGovernmentUnited States, North America

CIMIS Spatial ETo Reference Evapotranspiration Maps (California)

Daily grass-reference evapotranspiration (ETo) maps for California at 2 km resolution, plus weather-station ETo from 145+ agricultural weather stations. Designed to support irrigation scheduling and crop water demand estimation. Data available as spatial grids and station records back to 2004.

Open the sourceAsk WaterDataGPT

cimis.water.ca.gov

At a glance

Region
United States (North America)
Coverage
California
Access
Free
Category
Government
Last updated
2026

What's inside

  • evapotranspiration
  • weather station
  • irrigation
  • agriculture

Terms explained

What you can do with it

Typical work that data of this type supports.

  1. 01

    Irrigation scheduling

    Decide when and how much to irrigate.

    Because it has: evapotranspiration

  2. 02

    Water accounting

    Track how much water crops actually consume across a command area.

  3. 03

    Crop stress

    Spot water stress early in the season.

Where AI adds value

Ideas for machine learning and AI agents built on this kind of data.

  1. 01

    Field-scale ET

    Estimate crop water use per field by combining satellite and weather with ML.

  2. 02

    Demand forecasts

    Predict irrigation demand weeks ahead for canal and pump planning.

  3. 03

    Irrigated area maps

    Classify irrigated and rainfed fields from imagery.

Machine access and documentation

Open API

CIMIS RESTful Web API returns weather and spatial ETo data in JSON or XML (requires free app key).

Licence: Open data

Listed in our registry of open water APIs, which WaterDataGPT can query live.

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