As temperature, humidity, and solar orientation change from month to month throughout the year, so do the needs of your landscape. It is my experience that the general population makes only two adjustments to the timers that control the amount of water the landscape receives. On and off. It is estimated more than 50% of landscape water is wasted by wind drift, evaporation and overwatering.
If you have an irrigation controller with a 'Seasonal Adjust' feature, this chart can help guide you towards performing the proper adjustments to conserve water. Note that July is the basis with watering times at 100%. Being this is September, your irrigation controller should only be about 60%. When the time comes for the controller to be set lower than 50%, my recommendation is to actually increase the duration at that point and reduce the days watered. The roots appreciate a deeper watering so watering deeper with less frequency is advantageous to the flora instead of small, shallow watering.
Wind drift is a term to describe overspray due to breezy/windy conditions. Many irrigation valves have an adjustment screw on them for flow control. Typically I find that new controllers are in the 'wide open' position. Most sprinklers, however, mist heavily when receiving that much pressure so dial it down to reduce evaporation, but make sure you still get adequate coverage. Adjusting the direction the sprinkler heads are aimed so that you are not watering your patio, driveway or sidewalk is helpful too. Changing the sprinklers themselves to a more efficient style like MP Rotators can help dramatically.
The time of day the irrigation controller comes on is important as well. The middle of day is the warmest so watering during that time only leads to increased evaporation. A large part of the water is lost. 40-50% of it I read in one article. Watering at night is better but often the ground is still warm leading to higher evaporation again. Additionally, many bad bacterias and molds like warm, moist conditions so start growing. These can harm your plants and grasses. My recommendation is early morning waterings, before the sun comes up. Between the hours of 4am and 6pm, the sun is not quite awake yet giving an opportunity for the ground to take in the water.