Wet grass can clog your mower, leave ruts in the soil, and raise the risk of lawn diseases. Mowing wet grass isn't a good idea, so now you're wondering—do you need to squeeze in a quick mow before the storm hits? If you're in this predicament, is it better to mow before or after it rains? How Long To Wait After A RainIf life intervenes and you just don't have the time to mow, your lawn will survive. Just make sure you wait long enough so that you don't damage your lawn (or risk slipping) when you mow.