I base it on the dog ... and mine are all different. Chloe and Cookie are MUCH more heat tolerant than my previous dogs. Sass is probably the least heat tolerant dog I’ve ever owned. Yeah, it is hot out there today for sure. Glad it will cool off by Saturday as I have an outdoor show. Of course, Chloe’s worked a 198.5 in 95 degree weather in the sun before ... I on the other hand, am not as good in the heat as she is, LOL.