Avocado Irrigation Calculator using CIMIS

(California Irrigation Management Information System)

Updated March 13, 2024

Gary S. Bender

Farm Advisor Emeritus – Subtropical Horticulture

UC Cooperative Extension – San Diego County

The irrigation requirement can be calculated each week by using CIMIS (California Irrigation Management Information System). CIMIS is a network of weather stations throughout California that takes daily information on evapotranspiration (ETo) of eight-inch tall grass and sends this ETo to a computer in Sacramento. ETo is basically the amount of water lost each day from this grass; it is calculated in inches of water.   You can download this information when you want to irrigate your avocados and put it into an “irrigation calculator”. This information will be multiplied by the crop coefficient developed for avocados by UC Cooperative Extension farm advisors and specialists . This will give you the amount of water lost each day by avocados through transpiration and evaporation from the soil surface. Then, assuming the weather doesn't change, you can replace that amount of water when you irrigate.

Follow the Attached Files "CMIS exercise" link below to see how it's done.