Interview etiquette can be tricky, but it's important to get it right. Small things can end up making a big difference to the first impression you make when you walk into the interview room. Deciding whether or not to wear a coat, and then deciding where to put your coat once you arrive, can contribute to your confidence as you head in to meet the interviewer.
To Wear or Not to Wear?
You may decide not to wear a coat. Assuming you wear a suit to the interview, you already have a jacket. If the weather is not frigid, a coat may just be extra weight and one more thing to worry about. However, if it's snowing, raining or really cold, you may look odd if you turn up without a coat.
The coat you choose should look professional. Don't turn up with a ski jacket over your suit or something that's soiled or a loud color. A three-quarter length wool dress coat in a navy or other dark color is a good choice, and should coordinate with your suit. You could also choose a peacoat.
Where to Leave It
If you are able to park close to the building, consider leaving the coat in your car. That solves the dilemma before you enter the interview. If you have to walk some distance, or if you have arrived by taxi or public transport, you do not have this option. Once in the reception area, after you have introduced yourself to the receptionist, ask if there is a place you can hang your coat or if the receptionist can take it for you. Then leave it there when you go into the interview, retrieving it as you leave.
You may find an unstaffed reception and no obvious place to hang your coat. In this case, leave it on a chair in the reception area. You don't want to be juggling it as you try to shake the interviewer's hand and then trying to find a place to put it as you sit down. Take into the interview room only things that you need for the interview.