Watering requirements for your lawn will depend on a lot of different factors and will vary considerably from lawn to lawn and area to area. In general, in the hot summer months, lawn made from bluegrass or ryegrass will need about 2¼ inches of water every week. less in cooler weather. If your lawn is made from fescues less frequent watering is needed as this type of grass has a deeper root system and can store more moisture between waterings.
In the fall the cutting height of your mower should be gradually lowered in order to begin the winter with no tender young grass that will be susceptible to disease. In addition young grass will be vulnerable to drying out in the cold winter winds leaving you with a brown lawn. Lower the cutting height in steps so that the grass is gradually cut shorter or you may damage the turf by removing all the green growth.