Will an ultrasonic sensor detect objects on a rainy day?

The ultrasonic sensor is hardly affected by any environmental conditions, including smoky or rainy environments. However, if you want to use the ultrasonic ranging sensor outdoors for a long time, it is recommended to choose a waterproof ultrasonic sensor, such as the A02YYUW waterproof ultrasonic sensor  (SEN0311) or the waterproof ultrasonic ranging module (SEN0207).