NOTICES
CIMIS Overview

The following sections give a brief overview of CIMIS. Sections include the following: Introduction; Data Collection, Transmission, and Processing; Data Retrieval by Users; ETo Maps (Spatial CIMIS); and Trends in CIMIS Data Use. Please click on the arrow to the right of each title below to access the section.

  • Introduction
    The California Irrigation Management Information System (CIMIS) is a program unit in the Water Use and Efficiency Branch, Division of Statewide Integrated Water Management, California Department of Water Resources (DWR) that manages a network of over 145 automated weather stations in California. CIMIS was developed in 1982 by DWR and the University of California, Davis (UC Davis). It was designed to assist irrigators in managing their water resources more efficiently. Efficient use of water resources benefits Californians by saving water, energy, and money.
  • Data Collection, Transmission, and Processing
    Picture of the CIMIS network topology CIMIS weather stations collect weather data on a minute-by-minute basis. Hourly data reflects the previous hour's 60 minutes of readings. Hourly and daily values are calculated and stored in the dataloggers. A computer at the DWR headquarters in Sacramento calls every station starting at midnight Pacific Standard Time (PST) and retrieves data at predetermined time intervals. At the time of this writing, CIMIS data is retrieved from the stations every hour.

    When there is a communication problem between the polling server and any given station, the server skips that station and calls the next station in the list. After all other stations have reported, the polling server again polls the station with the communication problem. The interrogation continues into the next day until all of the station data have been transmitted.

    CIMIS data processing involves checking the accuracy of the measured weather data for quality, calculating reference evapotranspiration (ETo/ETr) and other intermediate parameters, flagging measured and calculated parameters, and storing the data in the CIMIS database. Evapotranspiration (ET) is a loss of water to the atmosphere by the combined processes of evaporation from soil and plant surfaces and transpiration from plants. Reference evapotranspiration is ET from standardized grass or alfalfa surfaces over which the weather stations are sitting. The standardization of grass or alfalfa surfaces for a weather station is required because ET varies depending on plant (type, density, height) and soil factors and it is difficult, if not impossible, to measure weather parameters under all sets of conditions. Irrigators have to use crop factors, known as crop coefficients (Kc), to convert ET from the standardized reference surfaces into an actual evapotranspiration (ETc) by a specific crop.
  • Data Retrieval by Users
    CIMIS weather stations are randomly distributed throughout California. It is very important that users select stations that represent the same microclimate as their area of interest. Resources to assist users in selecting representative weather stations include the CIMIS web site, local water districts, farm advisors, consultants, and CIMIS staff.

    Calculated parameters (such as ETo, net radiation, and dew point temperature) and measured parameters (such as solar radiation, air temperature, relative humidity, and wind speed) are stored in the CIMIS database for unlimited free access by registered CIMIS data users. Data can be retrieved using the CIMIS web site here.

    Data can be delivered to you via email on a given schedule. Email scheduling is available in two areas of the website after registering and logging in. Please click the DATA navigation bar, then My Reports, then under Custom Reports click on the ‘Edit’ button to adjust settings and to have CIMIS send data to your email. Also after logging in, click on the SPATIAL navigation bar and Schedule Spatial Report to set up emailing of Spatial data.

    In addition to the web, CIMIS offers an FTP site and web services for those interested in automated access to the data. The ftp site provides hourly and daily data for the previous 7 days and the previous 12 months. Also available at the ftp site is one year's worth of rolling daily ETo data, which means that the beginning and ending dates of this data advance forward by one day every day.

    Web Services for CIMIS includes the CIMIS Web API. This platform provides CIMIS data over SOAP and REST protocols free of charge. The RESTful services have been designed with a simplified interface that allows data to be queried by specific weather stations, zip codes, geographic coordinates, and even street addresses. New services allow users to get CIMIS station data as well a comprehensive list of supported zip codes for the Spatial and station systems. Please visit the CIMIS Web API website for more details.

    Contact information for CIMIS staff at the Sacramento headquarters and the DWR Regional Offices are provided in the CIMIS Staff tab on the Home Page. Questions regarding the selection of a CIMIS station, installation of new station, missing data, and information on how to use the data can be directed to the CIMIS staff in your DWR Regional Office. There are four DWR Regional Offices in California. If you have problems contacting the CIMIS staff in your Regional Office, you can Contact Us (DWRCIMISPublicContact@water.ca.gov) at the headquarters in Sacramento.

  • ETo Maps (Spatial CIMIS)
    The ETo Zones Map allows users to view the reference evapotranspiration (ETo) Zones for the State of California. This map divides the State into 18 zones based on long-term monthly average ETo values calculated using data from CIMIS weather stations.

    Many areas of California are not sufficiently covered by the network of randomly placed CIMIS stations. Recognizing these spatial data gaps, CIMIS in cooperation with the UC Davis developed a daily ETo map known as Spatial CIMIS. It provides daily ETo at 2-km grids for the entire State. The ETo maps are generated using complex sets of models. The input parameters to these models are combinations of data from satellites and ground measurements. Spatial CIMIS covers data from February 20, 2003 forward and can be accessed here

  • Trends in CIMIS Data Users
    Although CIMIS was initially designed to help agricultural growers develop water budgets for determining when to irrigate and how much water to apply, the user base has expanded over the years. Current CIMIS data users include landscapers, local water agencies, fire fighters, air control board, pest control managers, university researchers, school teachers, students, construction engineers, consultants, hydrologists, government agencies, utilities, lawyers, weather agencies, and many more.

    The number of registered CIMIS data users has also been growing steadily over the years. Currently, there are over 40,000 registered CIMIS data users. This number reflects only those registered users that are primary users of the CIMIS data. All users that are registered with CIMIS and have access to the archived CIMIS data are considered primary users. It has been established that thousands more users get CIMIS data from primary users. Examples include local water districts and consultants providing CIMIS data to their clients, newspapers providing ETo data to their subscribers, and websites providing CIMIS data to their customers. Users that get their data from sources other than the CIMIS database are referred to as secondary or tertiary users.

Getting Started

CIMIS provides data from two sources; CIMIS stations and Spatial CIMIS. Both types of data can be scheduled and emailed to you. Station data include measured parameters such as solar radiation, air temperature, soil temperature, relative humidity, wind speed, and wind direction and derived parameters such as vapor pressure, dew point temperature, reference and evapotranspiration (ETo). Spatial CIMIS data comes from satellite and CIMIS station data and consists of ETo and solar radiation only. Station data can be retrieved from the DATA navigation bar whereas Spatial CIMIS can be retrieved from the SPATIAL navigation bar.

Follow the steps below to access current and archived reference evapotranspiration (ETo) and station weather data. Non-registered users can retrieve current station data within preset parameters. Registered and logged in users have unlimited access to current and archived CIMIS data and all the website features, including email scheduling and SPATIAL data. Getting Started provides information about the following: Non-registered Users, Registered Users or To Register, Other Data Report Options for Registered – logged in Users, and Navigation Bar Content Summary. Please click on the arrow to the right of each title below to access the section.


  • Non-registered Users
    Limited Data
    • Click on the DATA navigation bar. Select the Limited Hourly, Limited Daily, or Limited Monthly Report style using the dropdown menu arrow. The time period for hourly is today's date and 7 days prior. The time period for daily data is the previous 7 days. Monthly data is the previous 12 months.
    • Select the unit of measure; English units are the default.
    • Choose a CIMIS station. Select one or more stations closest to the location you are interested in, taking into consideration best matches to your location’s microclimate. To select multiple stations, hold down the Shift or Ctrl key while clicking on multiple stations. Refer to the Station Location Map tab under the STATIONS navigation bar to verify what stations are closest to you.
    • Click on the Run Report button.
    • A web report will be displayed in a new browser tab page. If a report does not display, check your pop-up settings – including search engine toolbar pop-up settings – and allow pop-ups from this website. Then, try again.

    FTP Data
    • Click on the DATA navigation bar and select the FTP Reports link to select annual, daily, hourly, and monthly FTP data.
  • Registered Users or To Register
    Registration
    • The Login and Register links are located at the upper right corner of the web pages, or use the Login link on the DATA navigation bar. SPATIAL has a Spatial Reports Login tab.
    • Register by filling in the required information on the page. Registration is required for statistical purposes only and your information is not shared with any group or entity.

    Log in for unlimited data access
    • After logging in, you may access archived CIMIS data and a selection of reporting options. You can change your password any time on the Account page (link at upper right corner of the website). If you are logged out, the login link is also at the upper right corner of the web page.
    • Click on the DATA navigation bar. Select the Hourly, Daily, Daily ETo Variance, Monthly, or Monthly Average ETo Report style by using the dropdown menu arrow. The default time period for hourly is today's date and 7 days prior. The default time period for daily data is the previous 7 days. The Monthly default period is the previous 12 months.
    • Select a reporting method, the default is Web Report. The Web, XML (Extensible Markup Language), and PDF reports will display the data in a new browser page. Selecting CSV (Comma Separated Values) Report may provide the option to save or open the data. CSV opens in Microsoft Excel, notepad, or similar programs.
    • Choose English or Metric units. The default is English. Select a Date Range for the report.
    • Stations can be selected by status (Active or Inactive) and zip code. Specific sensors and hour ranges can be selected also on some reports.
    • Choose a CIMIS station. Select one or more stations closest to the location you are interested in, taking into consideration best matches to your location’s microclimate. To select multiple stations, hold down the Shift or Ctrl key while clicking on multiple stations. Refer to the Station Location Map tab under the STATIONS navigation bar to verify what stations are closest to you. If selecting by zip codes, separate them by a comma.
    • Click on the Run Report Button. If a report does not display, check your pop-up settings – including search engine toolbar pop-up settings – and allow pop-ups from this website. Then, try again.
    • Click on Logoff in the upper right corner to exit.
  • Other Data Report Options for Registered, logged in Users
    My Reports and Preferences
    • Click on the DATA navigation bar and select the My Reports and Preferences links (upper right). Select from up to 3 custom station lists and display quick custom reports using Preferences defaults. Use Preferences to set up station lists and to select defaults for output format, units of measure, and zip codes. Also set the date ranges for Quick and Custom Reports.
    • My Reports also includes an email scheduling option. Use the Custom Reports “Edit” link to create up to four customized reports and choose how often you will receive them by email.

    Schedule Spatial Reports
    • Click on the SPATIAL navigation bar to get ETo and Solar Radiation information from combined satellite and CIMIS Station data. Click on the Spatial Overview tab for more details.

    Web Services
    • Click on CIMIS Web API to access the web services website for a full explanation of this method of accessing CIMIS data.
    • Request a Web API AppKey after registering on our site by scrolling to the bottom of the 'Edit Accounts' page and clicking on the 'GetAppKey' button.
  • Navigation Bar Content Summary
    HOME
    • What the CIMIS data is, how the CIMIS system works, and who uses it. Use the Getting Started tutorial to sample current CIMIS data or get archived data. Contact your local or state CIMIS Staff. Find the latest news about the CIMIS station system and Frequently Asked Questions (FAQ) lists.

    STATIONS
    • See a listing of Active and Inactive CIMIS Stations. View a map of the CIMIS Station locations. Read the CIMIS Station siting criteria, station sensor list and details, and the maintenance program for stations.

    DATA
    • Select Hourly, Daily, Daily ETo Variance, Monthly or Monthly Average ETo reports. Set up your own Custom Reports, have them emailed to you, and select your report default Preferences.

    SPATIAL
    • See statewide Solar Radiation and ETo maps. Select up to 10 locations and have Spatial solar radiation and ETo data emailed to you.

    RESOURCES
    • Read extra information about the CIMIS program, CIMIS data, ETo, Irrigation and related publications. Find a listing of irrigation service consultants and software.
Staff
You may Email (DWRCIMISPublicContact@water.ca.gov)or call us at CIMIS headquarters in Sacramento or contact your Regional office below.  CIMIS Staff is generally available during normal business hours from 8 am to 5 pm. Regional Office Representatives listed below.
CIMIS Staff

Headquarters
901 P Street, 3rd Floor
P.O. Box 942836
Sacramento, CA 94236
fax: (916) 651-7059

Bekele Temesgen (916) 651-9679
Cayle Little (916) 654-6265
Jared Birdsall (916) 651-7218
Neil Rambo (916) 651-7015
Ricardo Trezza (916) 651-0763

Northern Region Office
2440 Main Street
Red Bluff, CA 96080
fax: (530) 529-7322

Mark Rivera (530) 529-7301

North Central Region Office
3500 Industrial Boulevard
West Sacramento, CA 95691
fax: (916) 376-9676

James Briggs (916) 376-9628

South Central Region Office
3374 East Shields Avenue
Fresno, CA 93726
fax: (559) 230-3301

Andrew Isner (559) 230-3384

Southern Region Office
770 Fairmont Avenue
Glendale, CA 91203
fax: (818) 543-4604

Robert Fastenau (818) 549-2319
Frequently Asked Questions
The following are Frequently Asked Questions (FAQ) regarding ETo, Reports, and General inquiries. Click to change categories and to show or hide answers.
General FAQs Report FAQs ETo FAQs