I can speak to May........we did not see many animals land, or sea-based during our 7-day cruise. A little too early and we were there in late May. Oddly, we went to Hawaii in January that same year and we saw many, many whales, so we did not miss them that much in Alaska. The weather was cool, but not much rain so it was a nice break from the Houston heat.
Even though we did not see any animals, we are planning on going back to Alaska, again in May.
i sailed on the ryndam may 8,2009 and we hit the jackpot on wildlife. I had been there before in June and late August with my late husband. Denali was a bust in1991. this time I went with my DD & SIL on an inside passage cruise. In juneau we took a HAL photo whale watch boat tour with about 18 others and a young photo guide. we went out and saw a number of whales almost immediately. the boat captain called other whale watch boats the location. I assume they were all males since the mamas and babies were still making the way up for the summer. there were also seals and sea lions. the rest of the tour involved a hike at Mendenhall Glacer. As we arrived at the drop off area a ranger approached our van and told us a bear was up a tree along the nature raised trail a short distance across the lot. naturally we all headed over and our guide judged it to be a teenager. from all I read bears weren't supposed to be around to the end of the month. when we returned to our ship there were humpbacks close by , closer than any I ever saw from any ship. and Glacier Bay was beautiful and many calving bergs. that with a buautiful flite at Misty Fjords with Michelle of Island wings made a memorable cruise for us
We have cruised to Alaska in both May and September. While the fall colors were beautiful in September, I much prefer May as the best time to cruise to Alaska. The mountains will still be covered with snow; the wildlife is just starting to come out from the long winter. We have seen many Whales in May, from the ship. That said, most sighting are from a good distance and do require a rather vigilant eye to spot them. The best way to see Wales close up, is to take a Whale sightseeing cruise out of Juneau.
One bit of warning is that Alaska can be habit forming; we decided to take a one-time cruise to Alaska about 17 years ago and have since taken 14 more cruise to Alaska.
Enjoy your cruise and visit to Alaska.
With integrity nothing else matters; without it nothing else matters.
If you want to see orcas, Alaska is sightings by pure chance. There are NO "tours" that will take you to see them. Both of these timeframes, has the POTENTIAL for whale sightings- the above posters, just did not plan tours, nor spent the considerable time, "watching" in the right areas. It isn't going to be a passive activity with you walking by a ship window, and whales being there. If you want to hedge your bets, then educate yourself on the most popular areas, spend a considerable amount of time on a forward deck, with the necessary pair of good wide angle binoculars. Then book yourself on tours. Humpback are seen on 100% of the trips out or Juneau and Hoonah.
IF Orcas are your priority, then I suggest you add several days and park yourself on Vancouver Island, and book several orca whale watches.
Overall, very early May and after the first week of Sept, you have the greatest chance of the worse weather potential. Problem also with Sept, of being dark by 7pm, cutting into daylight and touring time.