Both reference ET and rainfall data are important drivers of the irrigation recommendations in CropManage. If the weather data are not imported correctly into your plantings, then the irrigation recommendations may not be correct. CIMIS weather stations are generally reliable, but some stations may have a faulty sensor, or perhaps the rain gauge is recording precipitation events caused by sprinkler irrigations.
You should periodically check both the irrigation and the rainfall charts (tables) of at least one planting from each of your ranches. Compare the data in the left column (data used for calculating recommendations) of the table with the data from the weather station that you designated as the source for the planting. If the data match, then CropManage is correctly importing the data. Sometimes the rainfall data from the source weather station are from sprinkler rather than rain events. This can be determined by checking the rainfall data from other nearby CIMIS stations. If the other stations did not record rain events, then you should remove any incorrect rain events in the left column or change to another weather station source such as spatial CIMIS or a different CIMIS station.