High rainfall can cause floods in some communities. Therefore, we need a tool and system to monitor rainfall. This tool and system is designed by using Arduino Uno Microcontroller which is integrated with Rain sensor, Humidity, and Temperature sensor to monitor the weather. This application is designed to provide warnings and reports on the size of the rainfall level that can minimize the potential for flooding from the beginning. Analog and digital input data from Arduino are sent one by one to the Fuzzy Interface using serial protocols, the data processed using the Fuzzy Algorithm is used comparing the results of the Rain sensor, Humidity and Temperature sensor outputs. Comparison of sensor data will be generated a condition of the rule in accordance with the perception of a person in assessing a rain condition, the five conditions of this rule are, first Sunny, Cloudy, Drizzle, Wet, Heavy Rain. Testing of this system will be determined one rule as an alternative and the final decision of rainfall monitoring. This model provides an estimate of rainfall weather to remain rain level detection.