When Sam comes down the stairs after Robby closes the door on Miguel, she is wearing slippers. When she goes back upstairs, she is barefoot.
The students at Miyagi Do complain about the day being too hot to train, yet the Cobra Kai students are all wearing jackets at Coyote Creek.
These scenes occur simultaneously, and Coyote Creek can't be more than an hour's drive away, so the drastic weather differences are unlikely.