If the sun is out and it’s a beautiful day, what you see as a great day will most likely be very different for your dog.
Animals in general sleep and stay cool on hot days. Think twice about taking your dog out for your day in the sun. Most dogs would prefer a nice fun walk in the morning before it gets too hot and then will just chill out and sleep for most of the day, becoming more active as it cools down in the evening.
Pop Radio 4 on quietly, leave them a nice big bowl of water, and leave them to snooze during the hot part of the day while you go off and enjoy the heat!