No, you should not apply it during rain or immediately before it is about to rain. No, you should not apply this insecticide if you expect rain within 24 hours of using this compound. If it rains heavily within 24 hours after you have applied this compound, it will not dry completely.  If this insecticide will not dry properly, then your pet dogs and kids would be at risk of contamination with this insecticide.  Dogs can suffer from some mild symptoms of discomfort after coming in contact with this compound. The main factor is also dependent on your need for an application for insecticides.  If you are using this insecticide to kill the surface pests and insects, you should not let water get into 0.5 inches of the surface. After 24 hours, the rain will not affect the insecticide as by this time, and the compound will be hard and dry.