Okay so what do I do here... Nest eggs still hatching despite mom barely on!

[thistlewick]

3 successfully hatched little ones, I'm in amazement really.

She was set on them 100% for the first week but the last 2 weeks of incubation they were only set on at night and for a short period during the day when other ladies laid in that nest.

It has been continuously 85+ every day and slightly warmer inside the hen house - 4 degrees hotter when the wind isn't blowing.

 

[Wyorp Rock]

She was set on them 100% for the first week but the last 2 weeks of incubation they were only set on at night and for a short period during the day when other ladies laid in that nest.

It has been continuously 85+ every day and slightly warmer inside the hen house - 4 degrees hotter when the wind isn't blowing.

Very likely your hen is/was taking off the nest because of the heat. Your coop temp is approx. 90F(ish). Mama hen's body temp likely ranges 105-107F. That's a lot of heat to expose eggs to if she sits full time.
The eggs were plenty warm when it's cooler as she sat on them and she intermittently sat during the day.

I had a hen that sat Mid-Summer one year, daytime temps were in the 90s. For 3 weeks, she hung out near the nest but lounged with the other hens in the shade while keeping watch on her space. She sat on her eggs at night when it was cooler (60-75F). All 9 eggs hatched beautifully and on time. Happy, healthy thriving chicks that left the nest within 12hrs of hatch and were eating/drinking and exploring with Mama. Often nature does have a way of getting things right, in spite of us humans worrying about things so much.

Seriously. Just a thought, but maybe she didn't sit on them during the day because it was so hot and some instinct said it wasn't necessary? We're looking at a heat wave the next week with highs in the mid to upper 90's, lows in the 70's, heat indices however (the "feels like") are due to be well over 100°. Summer with a vengeance.