It is the week of the foreign exchange. While Smolder is the loving care of Yona's family, Yona is spending the week with Smolder's.

Smolder is unable to partake in yak traditions, since she has to stay in the fireplace or huddle Yona's parents' coat hair around herself to survive. Yona is having some trouble of her own. She can't safely participate in the dragons' most popular activities — since they all revolve around fighting, fire and lava — and the weather has been extreme.
The thick coat of a yak is designed to keep them both warm and cool, though the heat of Smolder's home land is a bit much.
The end of the dry season in Smolder's home land brings not only heat, but as the rain clouds roll in and the temperature drops, brings volatile, nigh apocalyptic storms as well. These storms trap Yona inside for the last three days of the exchange.

But she isn't confined to a cave during the first four, despite the high temperatures. Instead, she puts her hair up in a bun and gets to cool off and look for treasures at the beach, which is a pretty dragon thing to do still. Smolder's family has given her a string of green emeralds to hold her hair in place, because the color opposes red. Yona learns that the Dragon Lord has the sole right to publicly wear a headdress adorned with red stones, to prevent any confusion as to who currently holds the title.

When the other students learn that neither Smolder nor Yona got to truly participate in each other's customs, they feel bad for them. But both Smolder and Yona agree they didn't miss out on experiencing the culture, and say that the kindness of their host families showed them plenty.

Smolder in Yakyakistan: https://www.deviantart.com/queencold/art/The-foreign-exchange-student-861646064
Gallus in Ponyville: https://www.deviantart.com/queencold/art/Birthday-party-865449427
Sandbar in Griffonstone: https://www.deviantart.com/queencold/art/Archery-demonstration-914021243