Once the product has had time to dry (around 30 minutes), the treatment becomes water resistant so rain and watering shouldn't impact the effectiveness. Of course, the biggest indicator of whether the treatment has become ineffective is the presence of mosquitoes. Keep in mind we do guarantee our treatments for 21 days so if you are bothered by mosquitoes, let us know and we will apply a touch up treatment at no cost.
We also monitor the weather forecast closely and it's always a risk on cloudy days whether to spray or cancel. Since the weather forecast can change on a day to day basis, the decision to postpone treatments is usually a last minute one. If the forecast calls for heavy thunderstorms, we will reschedule treatment and notify you via email.