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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 Regional Assistance, 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. CIMIS data does not change to Daylight Savings Time (DST).

    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

Todd Flackus (707) 445-6576

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

Lida Shoeyb (559) 230-3369
Guillermo Coronado (559) 230-3388

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

Robert Fastenau (818) 549-2319
Rachel Cavanaugh (818) 549-2309

A new CIMIS Station #263 Smith River has been added to the network.
Friday, October 9, 2020
A new CIMIS Station #263 Smith River has been added to the network. The station is located north of Crescent City in Del Norte County.

Data will be missing from Stations #87, 116, 117, 215, 219 & 223.
Thursday, September 24, 2020
Data will be missing from Stations #87 Meloland, 116 Salinas North, 117 Victorville, 215 Chatsworth, 219 West Hills and 223 North Hollywood until phone service that was shutdown is restored.  Missing data will be intermittently posted as it is available.

Station #255 Chino will be missing data until the station is relocated and communications restored.
Friday, August 14, 2020
Data from Station #255 Chino will be missing until after the station is relocated nearby and phone communications are restored.  The historical data is still available.

Station#216 Arleta was vandalized and is not operating, historical data is available.
Friday, July 17, 2020
Station#216 Arleta was vandalized and is not operating, historical data is available.  There's been no decision on whether to make the repairs.

Cellular providers have notified us that some of the older generation station modems will lose service after Jan. 1st, 2020.
Thursday, July 2, 2020
Cellular providers have notified us that some of the older generation station modems will lose service after Jan. 1st, 2020. CIMIS station data and Spatial CIMIS may be affected. Station modems are being replaced with newer models.  Station data is continuing to be collected and stored at the station and will be made available once communication is restored.  Please check System News for updates.

Station #181 Westmorland North has been re-installed and is now providing data.
Friday, April 3, 2020
Station #181 Westmorland North has been re-installed and is now providing data. Please note that data from mid-July 2019 to early March 2020 will be missing.

Cadiz Valley Station 221 battery problems resolved
Friday, March 27, 2020
Station 221 Cadiz Valley has been repaired and is now providing full daily data. Data from November 2019 to March 2020 had been missing during non-daylight hours due to battery problems. Please take note.

A new CIMIS Station #262 Linden has been added to the network.
Friday, February 28, 2020
A new CIMIS Station #262 Linden has been added to the CIMIS network. The station is located near Linden, northeast of Stockton in San Joaquin County.

CIMIS Station #19 Castroville has been shut down, the historical data is available.
Thursday, December 26, 2019
CIMIS Station #19 Castroville has been shut down and will be removed, there is no cooperator for the station and the site is not being maintained. The historical data is available.

CIMIS Station #190 Five Points South West has been shut down, the historical data is available.
Thursday, December 26, 2019
CIMIS Station #190 Five Points South West has been shut down and will be removed, the research being done at the location has ended. The historical data is available.

CIMIS Station #146 Belridge has been repaired and is operating.
Friday, December 20, 2019
The vandalism to CIMIS Station #146 Belridge has been repaired and it is operating now.

A new CIMIS Station #260 Montague has been added to the network.
Monday, December 16, 2019
A new CIMIS Station #260 Montague has been added to the network. The station is located near Montague, northeast of Yreka in Siskiyou County.

A new CIMIS Station #261 Gazelle has been added to the network.
Monday, December 16, 2019
A new CIMIS Station #261 Gazelle has been added to the network. The station is located near Gazelle, south of Yreka in Siskiyou County.

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

Q
 What is CIMIS? show answer

Q
 How does CIMIS work? show answer

Q
 Can I get CIMIS data automatically delivered to my email? show answer

Q
 Where is the "My Reports" link and the "Schedule Spatial Report" tab? show answer

Q
 How do I set up Custom Report to send data to my email?  show answer

Q
 How do I schedule Spatial Reports to send data to my email? show answer

Q
 When was CIMIS established? show answer

Q
 Who owns the CIMIS stations? show answer

Q
 How many years of data are used to calculate CIMIS` historical (long-term average) data? show answer

Q
 What information is available from the Station List tab? show answer

Q
 What other information can I get from the CIMIS web site? show answer

Q
 What do I have to do to install a new CIMIS station in my area? show answer

Q
 Years ago I had an account. Can I still use it on the web? show answer

Q
 Why do I have to register to access CIMIS data? show answer

Q
 Whom do I contact if I have questions about CIMIS and its data? show answer

Q
 Is there a fee involved? show answer

Q
 My question isn't listed here! show answer

Q
 What kinds of data are available from CIMIS? show answer

Q
 Is the CIMIS data taken before or after the hour shown on the report? show answer

Q
 Does CIMIS use Daylight Savings Time? show answer

Q
 What Time Zone is CIMIS in? show answer

Q
 How can I access CIMIS data? show answer

Q
 How can I retrieve data from the CIMIS web site? show answer

Q
 Can I download CIMIS data automatically? show answer

Q
 What is a limited hourly report? show answer

Q
 Can I get real-time data from a CIMIS station? show answer

Q
 How much historical data can I retrieve from CIMIS? show answer

Q
 What is "wind run"? show answer

Q
 What is ETo? show answer

Q
 How can I use ETo data for irrigation scheduling? show answer

Q
 What is a crop coefficient (Kc) and how can I obtain it? show answer

Q
 How come ETo from CIMIS is greater than Precipitation? show answer

Q
 How is Monthly Average ETo Calculated? show answer

Q
 What is Daily ETo Variance? show answer