What are the best months to cruise to Alaska
The best dates to travel to and in Alaska really depends upon which part of Alaska you will be visiting and what you are most interested in. For instance, bear viewing is really popular, however most brown bear viewing is on the coast when the salmon are peaking out in the spawning streams, which occurs mid summer on.
If you are doing a cruise tour or visiting interior Alaska as an independent with a lot of outdoor activity, you might want to come before the peak mosquito season begins, shortly after mid June, ends around early August.
About 65% of cruisers to Alaska only do the Southeast (Panhandle) portion of the State. Not much of a mosquito problem in Southeast since they don't breed in brackish or salt water. Assuming you are on a typical 7 day (round robin) cruise you probably won't be crossing the Gulf of Alaska and traveling further north to South Central Alaska or going on into the interior on a land tour, but most likely doing a cruise of Southeast Alaska, originating and ending in either Vancouver or Seattle. Almost all of these cruises do the "Alaska Inside Passage". For Southeast you might want to wait until later June through mid September. Sometimes, close to the equinox, the Pacific storms start setting in, however, that also can be the best of the season too. Luck of the draw.
My personal preference for these round robins is to get on a cruise that cruises through the "Canadian Inside Passage" as well as the "Alaska Inside Passage". Meaning, they travel to the east of Vancouver Island as opposed to the west of the island, west of the island places the vessel out into the North Pacific where scenic voyaging is limited to non-existent, rougher water there too, particularly in the Fall. Vancouver is the most likely port for Canadian Inside Passage voyaging.
Beware when the line or your agent simply says you are going to be in the "Inside Passage". We are life long Alaskans so have taken only one cruise to Alaska, which was on Regent, a two weeker, originating in San Francisco and ending in Vancouver, around the end of May and first of June. Hot weather even, 72 F, for Alaska that is. We sailed as far north as Valdez in Prince William Sound and hit every obligatory port in Southeast. Excellent cruise; the only downer was, both north and south, we skipped the Canadian Inside Passage and traveled to the west of Vancouver Island. Some Canadians on board weren't very happy in that they had been led to believe they would be cruising on the east side of Vancouver island.
We have cruise Alaska in May and in August. We think that May is the best as you see more wildlife.
We went the first week of June and the weather was perfect. Lots of wildlife at that time too.
If you cruise late in the season late August & early September, fares are typically cheaper and lots of items are on sale clearance. Kids have gone back to school so ships are less crowded and if you go more north there is a better chance of seeing the Northern Lights. The only big disadvantage might be that some excursions may have shut down for the season.
If you live somewhere hot - you'll want to sail early in the season - May-June. If you don't care about that - Jul-Sept. Sept gets cool.