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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 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

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
Sergio Fierro (818) 549-2321

Stations #117, #147, #205 & #221 data will be intermittent.
Wednesday, January 25, 2017
CIMIS Stations #117 Victorville, #147 Otay Lake, #205 Coalinga and #221 Cadiz Valley will be posting data intermittently until the communications equipment is upgraded to resolve a cellphone service issue.

Stations #156 Oxnard & #194 Oakdale are shutdown
Wednesday, January 11, 2017
Stations #156 Oxnard and #194 Oakdale are shutdown until repaired and communications are restored.

CIMIS Stations #215 Chatsworth, #216 Arleta & #219 West Hills are shut down.
Tuesday, January 10, 2017
CIMIS Stations #215 Chatsworth, #216 Arleta & #219 West Hills are shut down until the communications equipment is upgraded to resolve the cellphone service issues.

Station #21 Kettleman is shut down until the phone line is repaired.
Thursday, January 5, 2017
Station #21 Kettleman is shut down until the phone line is repaired.  Current data will not be available, historical data is available on the website.

A new Station #251 Highland has been added to the CIMIS network.
Thursday, October 27, 2016
A new Station #251 Highland, near the community of Highland, in the eastern San Bernardino Valley, in San Bernardino County, has been added to the CIMIS network.

Station #136 Oasis is reconnected to the CIMIS network and the station data is now available.
Monday, September 19, 2016
The phone line at Station #136 Oasis has been repaired.  The Station is now reconnected to the CIMIS network and the station data is available.

Station #94 Goleta Foothills is shutdown until the phone line is repaired.
Tuesday, August 30, 2016
Station #94 Goleta Foothills is shutdown until the phone line is repaired.  Current data will not be available, historical data is available on the website.

A new CIMIS Station #250 Williams has been added to the CIMIS network.
Thursday, August 25, 2016
A new CIMIS Station #250 Williams, in Colusa County, has been added to the CIMIS network.

CIMIS Station #32 Colusa has been shut down and removed.
Friday, August 12, 2016
Station #32 Colusa has been shut down and removed.  Historical data is available and archived on the Inactive Stations list.

CIMIS Station #116 Salinas North will no longer be providing ETo Data.
Friday, August 5, 2016
Station #116 Salinas North has been changed to non-ETo status. ETo data will be provided again when the site conditions around the station are restored to the standard.

Four new Stations #243, 247, 248 and 249 have been added to the CIMIS network.
Tuesday, July 26, 2016
Four new CIMIS Stations #243 Ryde, near Walnut Grove, #247 Jersey Island, near Oakley, #248 Holt, near Stockton and #249 Ripon, near Manteca, have been added to the network.  See the Station List and Station Location Map on the CIMIS website for more information.

Station #85 Hopland FS is shutdown until the phone line is repaired.
Thursday, July 7, 2016
Station #85 Hopland FS is shutdown until the phone line is repaired.  Current data is not available, historical data is available on the website.

Station #140 Twitchell Island relocated.
Friday, June 17, 2016
June 16th, 2016 the station equipment location was changed to approximately one mile northwest.  The field is similar in size and use and is close enough to the original field to carry on a continuous data collection without changing station numbers.  Old location coordinates were 38.116125,-121.659210.

There's a new Non-ETo CIMIS Station #246 Markleeville
Tuesday, March 22, 2016
A new Non-ETo CIMIS Station #246 Markleeville has been installed east of the Sierra Nevada mountainns, about 5 miles north of Markleeville, in Alpine County.

Station #186 UC-San Luis is shutdown until repaired.
Tuesday, March 8, 2016
Station #186 UC-San Luis shutdown until repaired.  Current data is not available, the historical data is available on the website.

Station #203 Alpaugh is now a non-ETo station
Tuesday, February 16, 2016
Station #203 Alpaugh is now a non-ETo station.  The weather data from the station will be available, but the ETo won't be calculated.

ET-XML and FTP Changes
Monday, June 29, 2015
CIMIS has been providing data service through ET-XML and FTP since 2007. To keep up with current technology those services will be changing.  In the near future ET-XML will be discontinued; CIMIS Web API is its replacement.   The CIMIS FTP (ftp://ftpcimis.water.ca.gov/pub) will be moving into a new location (ftp://ftpcimis.water.ca.gov/pub2) and users may need to adjust their data format.  Check this page for updates.

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