Swan Hellenic Cruise - Dubrovnik/Jewel of Adriatic Cruise

You need to go to a cruise board to get a good insight, maybe Cruise Critic. Weather is available online, although global warming makes everything less predictable. If the cruise concentrates on Croatia, etc., you have done well to avoid a conventional Mediterranean cruise. If the ship is big, I worry about tendering delays. Take every chance you get to visit a town before or after tourist hours. Dubrovnik has a big (gangplank) pier but it is too far to walk to the historic city, for example

We went on a cruise along the Croatian coast a couple years ago in mid September and it was great. It could be cool in the mornings and evenings but was generally very nice during the day. A little warm in the middle of the day, especially in the sun or if you were hiking a city wall. A few people went swimming at some of our stops but for me it was a little cool. I would expect your trip will be a little cooler overall as it will be a little later in the month. We had almost perfect weather but the crew from our cruise told us that the week prior had lots of rain and they were dodging water spouts during some of the storms.

We went on a different cruise line, Star Clippers, so I cannot comment on your cruise line.

As Tim noted, your best bet for weather info is to check online. I was in the Balkans, including Croatia, from mid-August until October 13 last year. In late September the weather shifted from summer mode (too hot) to significantly cooler with some rain on about one out of every two days. I had a very light rain jacket as well as a warmer layer, and I was glad I had them both during the last 2 to 3 weeks of my trip. But that's just one person's experience in one year. Check online right before you leave for current projections.

Thanks for your prompt response. BP