Seeding with fescue is better done in the fall to prevent what you are experiencing. You have new grass growing during the spring, but dying in the heat of the summer as it is young and does not have well established roots. So in addition to the crab grass enjoying the heat of the summer and moving in while your cool season lawn grasses are going dormant(not dying), most of your new baby grass is dying.

If instead you overseed in the fall the grass will become established, survive through the winter, then have spring to grow more roots before it has to deal with the heat of the summer.

You can start killing the crabgrass now with roundup. It'll kill the grass also but you'll be reseeding in September anyway. Make sure you get a full sun or shade grass. There's lots of threads here with a step by step.

Good luck!

Thanks so much for all your help.

Just a few questions to follow up...

At what point in September would be the ideal time to reseed?

I think my lawn gets direct sun around 50% of the day (and there isn't much shade there). What would be the ideal mix or seed type to get the best results? I think I usually get the standard "sun and shade" mix, but maybe I don't have enough shade for that to work well.

Does watering 3x a week in the summer sound about right? How often in the fall after reseeding?

Is there anything that I can to do at this point (in early August) to spruce up the appearance, other than killing the crabgrass. I think my my wife may kill me if I tell her our lawn will look this way for the rest of the summer.

Thanks again for all your help

Eh?