Is there a max temp that hermanns tortoises can be outdoors? We frequently have temps around 100 degrees here. There is lots of shelter and logs to his under but is that too hot for hatchlings?
As long as the tortoise has a shady place to retreat to, it should be ok. If you have the baby in a tub of some sort, I'd bring it in in the afternoon when it's really hot.
You will need to use a thermometer and an infrared temp gauge in your enclosure to assess this. There are a lot of variables to consider. Open flat ground with a log hide will likely get to hot. Add some bushes, a shade tree over part of it, or an underground hide and you will probably be okay. Sprinklers or misters help on a hot day too. You must be careful with this. If their body temperature gets just a few degrees over 100, they can die. They don't have the ability to sweat and cool off like we do, so it is critical that you make sure they have cooler areas to retreat to if you are going to leave him outside during hot weather.