I know that you should cut the grass higher during the warmer months, but what about the rest of the year? Should I be cutting the lawn shorter towards the end of the year? Your input will be greatly appreciated.
The northern grass should never be cut shorter than 3" during the summmer months, but in the spring and fall, you can bring it down to 2" to 2.5". I always do it this way. In the dry months I might bring it up to 3.5 to 4". By cutting it shorter in the fall, you help eliminate winter kill up north from snow.
I'd be concerned with cutting short in the spring. When you cut short early you allow more sunlight to be absorbed by germinating weeds, especially crabgrass. This stimulates the crabgrass and can make control of it tougher. By cutting the grass at your normal height, you help keep the grass ahead of the undesirable weeds.