Yes, too much heat will slow down or stop their laying.
It helps if they have plenty of shade, a breeze, and cool clean water to drink, and water they can get into up to their bellies during a hot spell. Mine continue to lay but I work at keeping them cool. I keep a shade cloth over the outside of their house, too, and that drops the inside temperature by 5 to 10 degrees.
I give them peas just thawed so they are plenty cool, once a day, too.
It might help to give them vitamins during this stressful time.