Try keeping them in their shed for a day maybe even 2 , make sure they have food and water in there with them. Then if you keep try to check a couple of times during the day you should be able to tell if they are laying or not.
If it's very hot I wouldn't shut them in, do it on a cooler day.
We also find when it's very hot egg production goes down.Also sometimes a move can unsettle them and it can take a wee while to start laying again, this could be the case if you've not had them for long.