How long overdue should you let eggs go under hen

[16Chickens]

We have raised several clutches with our hens. We have to get fertilized eggs from a family member with a rooster, so not 100% on fertility. It's day 24 and I'm curious if cooler template outdoors would cause slower development or later hatch. I know in incubation temp is important, and that mom is perfect for eggs, but it got down in the 40s one week and made me wonder if this would slow them down. Any thoughts?

 

[Rod-T]

Some should have hatched by now I think

 

[Pork Pie]

I would not think so

 

[FridayYet]

You might want to candle them to see what's going on.

 

[sumi]

Candle them and check… I've had an egg hatch under a broody in "perfect" conditions on day 25 once, so anything is possible?

 

[16Chickens]

Ok, here's an update. The chicken eggs were not fertile. No I didn't candle them early on or anything, we never had before and never had issues getting chicks, so I didn't think I needed to this time. But, my cousin thought it would be fun to put two duck eggs in the clutch. She wanted to suprise my kids. Since I knew duck eggs take longer, I left the chicken eggs under her longer than I would have, but on night 25 we went to local farm store, bought some week old chicks, and I put them under her while she slept. I did grab a couple of easy to get eggs out from under her as I did this. The next morning I went to check on her to see if she had accepted chicks, and she had. And they just seem to enjoy having a mamma so much! I also discovered one of the ducks had started hatching (day 26) which I was relieved because I anticipated having to keep eggs under her until day 28. By the end of the day we had two ducklings as well! So I removed the rest of the old eggs and have been enjoying watching this new mamma with her little family!
(I would have waited until closer to duck hatching day to get the chicks, but my daughter wanted Rhode Island Reds and the store was about to sell out and not sure when they would get more.)