In my opinion, it's too late. You'd probably be waisting your time and money. Wait until fall.

The Univ of GA recommends April for spring overseeding. But better to wait until fall if you can.

If you overseed now, you will need to water once per week with at least one inch of water through the summer to keep it from dying in the heat. Even then you may not be very successful. Watering more often than that may cause disease in the established grass.

Fall is the best time to overseed. The roots can get established before the summer heat.

Rent a machine or pay a landscaper to plug aerate your lawn. That helps to loosen the soil so the roots grow deeper.

Cut fescue with a SHARP mower blade as late in the day as possible. To help fescue get through the heat, set the mower so the grass is at least 2 inches high after you cut. I have my mower on the highest setting. For healthiest fescue cut no more than one-third of plant height when you mow. So that means cut before it gets 3 inches high, if possible.

You have to water to an inch a week anyway don't you???

If UGA recommends April for overseeding, what's the problem? This is the middle of April.

It doesn't really "recommend" doing it in april, just that it's possible to do it in april as opposed to june. Obviously you want the grass to get established as far ahead of extreme heat and cold as possible.

If you are trying to establish a new lawn, forget it. If you are filling in dead patches go ahead and do it soon before temps go up to 90°. Forecasted highs for the next ten days already include some 80s and evening lows are going to get into the 50s which is a bit high for good root growth. It's the cool nights that send the roots down deep and I am affraid they're about gone.

Great info, vroomp. Thanks for the explanation about cool nights.