Can chicken eggs hatch with heat on only half the time?

[AWholeBunchOfChickens]

(These are the two hens) I have a couple fertilized chicken eggs under two broody hens. The hens take turns sitting on the eggs and sometimes they won't sit on the eggs unless I put the hen in the nest. Will the eggs be okay if they only have heat half the time? Or should I do something?

 

[ChickenCanoe]

No. They need a relatively constant temperature of 99.5F. In the first few days, they can have cooling periods but not for very long.
I assume they are young pullets leaning to set.

 

[AWholeBunchOfChickens]

No. They need a relatively constant temperature of 99.5F. In the first few days, they can have cooling periods but not for very long.
I assume they are young pullets leaning to set.

Yeah they are but they are now sitting on their eggs full time, thank you though! : )