Bartimaeus is always dressing for the seasons. When he changes his attire, I know that the weather is about to alter abruptly.
Here he is during the colder months (Bartimaeus has asked for a scarf on numerous occasions, but after we investigated the possibilities, Bartimaeus and I decided that he has no real use for one, i.e., no neck):
Below is Bartimaeus in the warmer months (he’s just recently changed):
Bartimaeus wears many outfits throughout the year, but these two are the most common.