Where are you located? What kind of grass did you seed? Did you water the seed? Some pictures would be helpful.

Located in WI and I am assuming its bluegrass/fescue mix. I was told watering in would not be necessary since it was the whole yard(I do believe we received rain later on that week).

I attached a picture and it is not the greatest picture because I just mowed the lawn today so they are not that noticeable yet but these spots will become more prominent in the coming days and very obvious. They are in numerous spots throughout the yard. I am assuming it will eventually blend in but not sure if I needed to do something. Is this common?

Sounds like your lawn care folks had a boat payment coming up. You do need to water the seed, and the seed needs to stay continuously moist for up to 3 weeks in the case of KBG, otherwise what you get is abysmal to no germination.

Anything that was going to germinate germinated in the fall or spring at the latest. Probably a summer weed at this point. Please take a few pictures of the dark spots, maybe one from about 2 feet that includes both your normal grass and the dark spot, and one closer so the grass blades are clearly visible. Try to take the pictures in the shade or on a cloudy day, in full sun the contrast is too high and you can't tell one thing from another.

What's your height of cut? Fescue should be cut at 3.5 to 4 inches. I can't really tell from the picture but the cut seems low.

Thanks for the help. I always set the mower at 3 or 3.5. I attached a couple of photos of the same area but in the shade now. As I said before this just started happening around second week of May so perhaps it is not from the overseeding? But those spots are popping up in a lot of places in the yard now not just this area but they all look the same.

Any pets?

Do you have a dog that could be adding nitrogen in those spots?

I have a dog but he is trained to go on the mulch, which he does 95% of the time. I did think of this and if he does go we usually try and water it(could be making the area greener?) I travel a lot and my wife was on maternity leave from march-may and claims he may have been going out in the yard more frequently then normal as opposed to the mulch.

And to add to it, I would say that the most common areas that he would go on if he does not use the mulch would be the highest concentration of these new darker spots but not all of them.

I think that's it, the grass is darker from the extra nitrogen and water.

Good news is, your lawn could be that dark and healthy with a little more nitrogen and water!

Yeah likely the dog and if it's small then it would make sense to see the dark spots without it dying. If you see those spots start to die, pour some sugar in it.

He's a 125 lb Swiss mountain dog. We did not have this problem at all with him last year but he was 2 months old in May. Our last one would sizzle the yard if we did not water it afterwards.

Should I just apply a heavy rate fertilizer down? Would that blend it all together or would that potentially burn those areas?

Ok thanks for the help.