I have only been on two cruises and they have been to hot places so I know that air conditioning is on. I do not know how to pack for a cruise to Canada in October, I hate hot stuff rooms, do they keep the interiors of the ship warm?
Also remember that newer ships often have better A.C. than some of the older vessels. That is one good reason to have a balcony. At least you can get fresh air as needed, even if the sign by the door says it is a "no-no" to prop open the door.
Salem if you're coming to Canada in October, you'd better bring lots of warm clothes! You will definately need long pants and jackets if you're outside. (Where exactly are you going?) As for indoors, I was just recently in the Caribbean (hot, hot, hot) and our cabin steward every day would turn the a.c. on high, and I would turn it off and onto "heat" every night, it was so cold in our room, so I'd hope there's be heat elsewhere in the ship too!
the cruise lines try to keep their ships at a comfortable level when it comes to heating and cooling. Your cabin with have heat & ac as do the common rooms. I would pack cool weather clothes - chino type or jean pants with a jersey top and good walking sneakers for shore excursions. I would also pack a sweatshirt, light rain jacket, a cardigan sweater or a linen or cotton blazer for evenings - the dining rooms on most cruise lines for some reason always seem a bit chilly for me. I would pack a couple of pairs of shorts & your bathing suit incase you run into some "Indian Summer" weather.
Salem, I'm in Montreal and I could probably wave to you from the Old Port as you pass through up the St. Lawrence River! In addition to your warm clothes, Lisa's right, you could experience "Indian Summer" and need some lighter clothes. We were married on Sept. 29 at an outdoor Railway Museum near Montreal, and it was a beautiful Indian Summer kind of day, kinda hot in the rented Victorian garb we were wearing!
If your from a warmer region and cruising in eastern Canada, I would suggest taking clothes that can be layered. Long sleeve shirts, sweaters, wind/water resistant jacket, long pants etc.. We have been known to get warm days in this area in October but remember, it is autumn. We have cruise ships stopping over here (Newfoundland) and folks generally can expect pleasant weather in the fall, but it can turn cold and wet.
I was on a trans Panama canal cruise in 2001 from San Diego to Fort Lauderdale aboard the Mercury, and am looking forward to number two, just have not decided which cruise or when to take it.